diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 52473045..d50f717a 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -36,4 +36,4 @@ jobs:
           tag="${{ github.ref_name }}"
           body="Release $tag"
           gh release create --draft "$tag" --title "$tag" --notes "$body" --generate-notes
-          gh release upload "${{ github.ref_name }}" packages/powersync/assets/powersync_db.worker.js
+          gh release upload "${{ github.ref_name }}" packages/powersync/assets/powersync_db.worker.js packages/powersync/assets/powersync_sync.worker.js
diff --git a/.gitignore b/.gitignore
index 460fc6b7..1baa751f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,8 @@ assets/*
 powersync_db.worker.js
 powersync_db.worker.js*
 sqlite3.wasm
+powersync_sync.worker.js
+powersync_sync.worker.js*
 
 #Core binaries
 *.dylib
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce8714ce..f40c39ea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,31 @@
 All notable changes to this project will be documented in this file.
 See [Conventional Commits](https://conventionalcommits.org) for commit guidelines.
 
+## 2024-11-01
+
+### Changes
+
+---
+
+Packages with breaking changes:
+
+ - There are no breaking changes in this release.
+
+Packages with other changes:
+
+ - [`powersync` - `v1.9.0`](#powersync---v190)
+ - [`powersync_attachments_helper` - `v0.6.14`](#powersync_attachments_helper---v0614)
+
+---
+
+#### `powersync` - `v1.9.0`
+
+ - **FEAT**: Use a sync worker for web that offloads the task of synchronizing databases to a separate worker, allowing it to be coordinated across tabs even when the database itself is not in a shared worker.
+
+#### `powersync_attachments_helper` - `v0.6.14`
+
+ - Update a dependency to the latest release.
+
 ## 2024-10-31
 
 ### Changes
@@ -62,7 +87,7 @@ Packages with other changes:
 
 #### `powersync_flutter_libs` - `v0.4.1`
 
-  - powersync-sqlite-core v0.3.4
+ - powersync-sqlite-core v0.3.4
 
 ## 2024-10-17
 
diff --git a/demos/django-todolist/.metadata b/demos/django-todolist/.metadata
new file mode 100644
index 00000000..391c336b
--- /dev/null
+++ b/demos/django-todolist/.metadata
@@ -0,0 +1,45 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "5874a72aa4c779a02553007c47dacbefba2374dc"
+  channel: "stable"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+    - platform: android
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+    - platform: ios
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+    - platform: linux
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+    - platform: macos
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+    - platform: web
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+    - platform: windows
+      create_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+      base_revision: 5874a72aa4c779a02553007c47dacbefba2374dc
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'
diff --git a/demos/django-todolist/android/app/src/main/kotlin/co/powersync/django_todolist/MainActivity.kt b/demos/django-todolist/android/app/src/main/kotlin/co/powersync/django_todolist/MainActivity.kt
new file mode 100644
index 00000000..f5cbc4a3
--- /dev/null
+++ b/demos/django-todolist/android/app/src/main/kotlin/co/powersync/django_todolist/MainActivity.kt
@@ -0,0 +1,5 @@
+package co.powersync.django_todolist
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity: FlutterActivity()
diff --git a/demos/django-todolist/ios/RunnerTests/RunnerTests.swift b/demos/django-todolist/ios/RunnerTests/RunnerTests.swift
new file mode 100644
index 00000000..86a7c3b1
--- /dev/null
+++ b/demos/django-todolist/ios/RunnerTests/RunnerTests.swift
@@ -0,0 +1,12 @@
+import Flutter
+import UIKit
+import XCTest
+
+class RunnerTests: XCTestCase {
+
+  func testExample() {
+    // If you add code to the Runner application, consider adding tests here.
+    // See https://developer.apple.com/documentation/xctest for more information about using XCTest.
+  }
+
+}
diff --git a/demos/django-todolist/lib/powersync.dart b/demos/django-todolist/lib/powersync.dart
index 4a40b4a2..0b4b9277 100644
--- a/demos/django-todolist/lib/powersync.dart
+++ b/demos/django-todolist/lib/powersync.dart
@@ -1,4 +1,5 @@
 // This file performs setup of the PowerSync database
+import 'package:flutter/foundation.dart';
 import 'package:logging/logging.dart';
 import 'package:path/path.dart';
 import 'package:path_provider/path_provider.dart';
@@ -99,8 +100,14 @@ Future<bool> isLoggedIn() async {
 }
 
 Future<String> getDatabasePath() async {
+  const dbFilename = 'powersync-demo.db';
+  // getApplicationSupportDirectory is not supported on Web
+  if (kIsWeb) {
+    return dbFilename;
+  }
+
   final dir = await getApplicationSupportDirectory();
-  return join(dir.path, 'powersync-demo.db');
+  return join(dir.path, dbFilename);
 }
 
 // opens the database and connects if logged in
diff --git a/demos/django-todolist/pubspec.lock b/demos/django-todolist/pubspec.lock
index 493d86c9..0b94745e 100644
--- a/demos/django-todolist/pubspec.lock
+++ b/demos/django-todolist/pubspec.lock
@@ -152,6 +152,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.0.2"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.1"
   json_annotation:
     dependency: transitive
     description:
@@ -164,18 +172,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -212,18 +220,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mutex:
     dependency: transitive
     description:
@@ -310,14 +318,14 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -439,10 +447,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   stack_trace:
     dependency: transitive
     description:
@@ -479,10 +487,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   typed_data:
     dependency: transitive
     description:
@@ -519,10 +527,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   web:
     dependency: transitive
     description:
diff --git a/demos/django-todolist/pubspec.yaml b/demos/django-todolist/pubspec.yaml
index 317acd12..6d522820 100644
--- a/demos/django-todolist/pubspec.yaml
+++ b/demos/django-todolist/pubspec.yaml
@@ -10,11 +10,11 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  powersync: ^1.8.9
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   path: ^1.8.3
   logging: ^1.2.0
-  sqlite_async: ^0.9.0
+  sqlite_async: ^0.10.1
   http: ^1.2.1
   shared_preferences: ^2.2.3
 
diff --git a/demos/django-todolist/web/favicon.png b/demos/django-todolist/web/favicon.png
new file mode 100644
index 00000000..8aaa46ac
Binary files /dev/null and b/demos/django-todolist/web/favicon.png differ
diff --git a/demos/django-todolist/web/icons/Icon-192.png b/demos/django-todolist/web/icons/Icon-192.png
new file mode 100644
index 00000000..b749bfef
Binary files /dev/null and b/demos/django-todolist/web/icons/Icon-192.png differ
diff --git a/demos/django-todolist/web/icons/Icon-512.png b/demos/django-todolist/web/icons/Icon-512.png
new file mode 100644
index 00000000..88cfd48d
Binary files /dev/null and b/demos/django-todolist/web/icons/Icon-512.png differ
diff --git a/demos/django-todolist/web/icons/Icon-maskable-192.png b/demos/django-todolist/web/icons/Icon-maskable-192.png
new file mode 100644
index 00000000..eb9b4d76
Binary files /dev/null and b/demos/django-todolist/web/icons/Icon-maskable-192.png differ
diff --git a/demos/django-todolist/web/icons/Icon-maskable-512.png b/demos/django-todolist/web/icons/Icon-maskable-512.png
new file mode 100644
index 00000000..d69c5669
Binary files /dev/null and b/demos/django-todolist/web/icons/Icon-maskable-512.png differ
diff --git a/demos/django-todolist/web/index.html b/demos/django-todolist/web/index.html
new file mode 100644
index 00000000..79c42864
--- /dev/null
+++ b/demos/django-todolist/web/index.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <!--
+    If you are serving your web app in a path other than the root, change the
+    href value below to reflect the base path you are serving from.
+
+    The path provided below has to start and end with a slash "/" in order for
+    it to work correctly.
+
+    For more details:
+    * https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
+
+    This is a placeholder for base href that will be replaced by the value of
+    the `--base-href` argument provided to `flutter build`.
+  -->
+  <base href="$FLUTTER_BASE_HREF">
+
+  <meta charset="UTF-8">
+  <meta content="IE=Edge" http-equiv="X-UA-Compatible">
+  <meta name="description" content="A new Flutter project.">
+
+  <!-- iOS meta tags & icons -->
+  <meta name="apple-mobile-web-app-capable" content="yes">
+  <meta name="apple-mobile-web-app-status-bar-style" content="black">
+  <meta name="apple-mobile-web-app-title" content="django_todolist">
+  <link rel="apple-touch-icon" href="icons/Icon-192.png">
+
+  <!-- Favicon -->
+  <link rel="icon" type="image/png" href="favicon.png"/>
+
+  <title>django_todolist</title>
+  <link rel="manifest" href="manifest.json">
+</head>
+<body>
+  <script src="flutter_bootstrap.js" async></script>
+</body>
+</html>
diff --git a/demos/django-todolist/web/manifest.json b/demos/django-todolist/web/manifest.json
new file mode 100644
index 00000000..aa135b47
--- /dev/null
+++ b/demos/django-todolist/web/manifest.json
@@ -0,0 +1,35 @@
+{
+    "name": "django_todolist",
+    "short_name": "django_todolist",
+    "start_url": ".",
+    "display": "standalone",
+    "background_color": "#0175C2",
+    "theme_color": "#0175C2",
+    "description": "A new Flutter project.",
+    "orientation": "portrait-primary",
+    "prefer_related_applications": false,
+    "icons": [
+        {
+            "src": "icons/Icon-192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "icons/Icon-512.png",
+            "sizes": "512x512",
+            "type": "image/png"
+        },
+        {
+            "src": "icons/Icon-maskable-192.png",
+            "sizes": "192x192",
+            "type": "image/png",
+            "purpose": "maskable"
+        },
+        {
+            "src": "icons/Icon-maskable-512.png",
+            "sizes": "512x512",
+            "type": "image/png",
+            "purpose": "maskable"
+        }
+    ]
+}
diff --git a/demos/supabase-anonymous-auth/pubspec.lock b/demos/supabase-anonymous-auth/pubspec.lock
index abf60908..4272f3f3 100644
--- a/demos/supabase-anonymous-auth/pubspec.lock
+++ b/demos/supabase-anonymous-auth/pubspec.lock
@@ -184,6 +184,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.0.2"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.1"
   json_annotation:
     dependency: transitive
     description:
@@ -204,18 +212,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -252,18 +260,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mime:
     dependency: transitive
     description:
@@ -366,14 +374,14 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -519,10 +527,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   stack_trace:
     dependency: transitive
     description:
@@ -583,10 +591,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   typed_data:
     dependency: transitive
     description:
@@ -687,10 +695,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   web:
     dependency: transitive
     description:
diff --git a/demos/supabase-anonymous-auth/pubspec.yaml b/demos/supabase-anonymous-auth/pubspec.yaml
index 6550e3e1..3d334007 100644
--- a/demos/supabase-anonymous-auth/pubspec.yaml
+++ b/demos/supabase-anonymous-auth/pubspec.yaml
@@ -11,12 +11,12 @@ dependencies:
   flutter:
     sdk: flutter
 
-  powersync: ^1.8.9
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   supabase_flutter: ^2.0.2
   path: ^1.8.3
   logging: ^1.2.0
-  sqlite_async: ^0.9.0
+  sqlite_async: ^0.10.1
   universal_io: ^2.2.2
 
 dev_dependencies:
diff --git a/demos/supabase-edge-function-auth/pubspec.lock b/demos/supabase-edge-function-auth/pubspec.lock
index df4ee35d..4c5f4742 100644
--- a/demos/supabase-edge-function-auth/pubspec.lock
+++ b/demos/supabase-edge-function-auth/pubspec.lock
@@ -208,6 +208,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.0.2"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.1"
   json_annotation:
     dependency: transitive
     description:
@@ -228,18 +236,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -276,18 +284,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mime:
     dependency: transitive
     description:
@@ -390,14 +398,14 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -543,10 +551,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   stack_trace:
     dependency: transitive
     description:
@@ -607,10 +615,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   typed_data:
     dependency: transitive
     description:
@@ -711,10 +719,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   web:
     dependency: transitive
     description:
diff --git a/demos/supabase-edge-function-auth/pubspec.yaml b/demos/supabase-edge-function-auth/pubspec.yaml
index 4a9d4985..22ff47c6 100644
--- a/demos/supabase-edge-function-auth/pubspec.yaml
+++ b/demos/supabase-edge-function-auth/pubspec.yaml
@@ -11,12 +11,12 @@ dependencies:
   flutter:
     sdk: flutter
 
-  powersync: ^1.8.9
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   supabase_flutter: ^2.0.2
   path: ^1.8.3
   logging: ^1.2.0
-  sqlite_async: ^0.9.0
+  sqlite_async: ^0.10.1
   universal_io: ^2.2.2
 
 dev_dependencies:
diff --git a/demos/supabase-simple-chat/pubspec.lock b/demos/supabase-simple-chat/pubspec.lock
index c80d9f53..d1970795 100644
--- a/demos/supabase-simple-chat/pubspec.lock
+++ b/demos/supabase-simple-chat/pubspec.lock
@@ -224,6 +224,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.19.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.1"
   json_annotation:
     dependency: transitive
     description:
@@ -244,18 +252,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -292,18 +300,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mime:
     dependency: transitive
     description:
@@ -406,14 +414,14 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -559,10 +567,10 @@ packages:
     dependency: transitive
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   stack_trace:
     dependency: transitive
     description:
@@ -623,10 +631,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   timeago:
     dependency: "direct main"
     description:
@@ -735,10 +743,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   web:
     dependency: transitive
     description:
diff --git a/demos/supabase-simple-chat/pubspec.yaml b/demos/supabase-simple-chat/pubspec.yaml
index f0a1c9c6..0599c9b0 100644
--- a/demos/supabase-simple-chat/pubspec.yaml
+++ b/demos/supabase-simple-chat/pubspec.yaml
@@ -37,7 +37,7 @@ dependencies:
 
   supabase_flutter: ^2.0.2
   timeago: ^3.6.0
-  powersync: ^1.8.9
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   path: ^1.8.3
   logging: ^1.2.0
diff --git a/demos/supabase-todolist-drift/pubspec.lock b/demos/supabase-todolist-drift/pubspec.lock
index b402e028..79c1df3d 100644
--- a/demos/supabase-todolist-drift/pubspec.lock
+++ b/demos/supabase-todolist-drift/pubspec.lock
@@ -301,10 +301,10 @@ packages:
     dependency: "direct main"
     description:
       name: drift_sqlite_async
-      sha256: cf5cba587b29e3cebaf5abefaa3f61be7e2232d9a0d9bcc0ba64341f3e77ac88
+      sha256: fc5450654ccacd5cbba627d7d86d0dd84e26070941c2a068eb8298fb86a01cd3
       url: "https://pub.dev"
     source: hosted
-    version: "0.2.0-alpha.1"
+    version: "0.2.0-alpha.3"
   fake_async:
     dependency: transitive
     description:
@@ -500,18 +500,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -548,18 +548,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mime:
     dependency: transitive
     description:
@@ -686,21 +686,21 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_attachments_helper:
     dependency: "direct main"
     description:
       path: "../../packages/powersync_attachments_helper"
       relative: true
     source: path
-    version: "0.6.12"
+    version: "0.6.14"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -878,10 +878,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   sqlparser:
     dependency: transitive
     description:
@@ -958,10 +958,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   timing:
     dependency: transitive
     description:
@@ -1070,10 +1070,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   watcher:
     dependency: transitive
     description:
diff --git a/demos/supabase-todolist-drift/pubspec.yaml b/demos/supabase-todolist-drift/pubspec.yaml
index bf77f1a9..dce8d221 100644
--- a/demos/supabase-todolist-drift/pubspec.yaml
+++ b/demos/supabase-todolist-drift/pubspec.yaml
@@ -9,8 +9,8 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  powersync_attachments_helper: ^0.6.13
-  powersync: ^1.8.9
+  powersync_attachments_helper: ^0.6.14
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   supabase_flutter: ^2.0.1
   path: ^1.8.3
@@ -18,9 +18,9 @@ dependencies:
   camera: ^0.10.5+7
   image: ^4.1.3
   universal_io: ^2.2.2
-  sqlite_async: ^0.9.0
+  sqlite_async: ^0.10.1
   drift: ^2.20.2
-  drift_sqlite_async: ^0.2.0-alpha.1
+  drift_sqlite_async: ^0.2.0-alpha.3
 
 dev_dependencies:
   flutter_test:
diff --git a/demos/supabase-todolist-optional-sync/pubspec.lock b/demos/supabase-todolist-optional-sync/pubspec.lock
index 87a21435..c45bc8f7 100644
--- a/demos/supabase-todolist-optional-sync/pubspec.lock
+++ b/demos/supabase-todolist-optional-sync/pubspec.lock
@@ -280,6 +280,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.2.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.1"
   json_annotation:
     dependency: transitive
     description:
@@ -300,18 +308,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -348,18 +356,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mime:
     dependency: transitive
     description:
@@ -470,14 +478,14 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -623,10 +631,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   stack_trace:
     dependency: transitive
     description:
@@ -695,10 +703,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   typed_data:
     dependency: transitive
     description:
@@ -799,10 +807,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   web:
     dependency: transitive
     description:
diff --git a/demos/supabase-todolist-optional-sync/pubspec.yaml b/demos/supabase-todolist-optional-sync/pubspec.yaml
index 94f83b9d..f92df9ad 100644
--- a/demos/supabase-todolist-optional-sync/pubspec.yaml
+++ b/demos/supabase-todolist-optional-sync/pubspec.yaml
@@ -10,7 +10,7 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  powersync: ^1.8.9
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   supabase_flutter: ^2.0.1
   path: ^1.8.3
@@ -18,7 +18,7 @@ dependencies:
   camera: ^0.10.5+7
   image: ^4.1.3
   universal_io: ^2.2.2
-  sqlite_async: ^0.9.0
+  sqlite_async: ^0.10.1
 
 dev_dependencies:
   flutter_test:
diff --git a/demos/supabase-todolist/ios/Runner/AppDelegate.swift b/demos/supabase-todolist/ios/Runner/AppDelegate.swift
index 70693e4a..b6363034 100644
--- a/demos/supabase-todolist/ios/Runner/AppDelegate.swift
+++ b/demos/supabase-todolist/ios/Runner/AppDelegate.swift
@@ -1,7 +1,7 @@
 import UIKit
 import Flutter
 
-@UIApplicationMain
+@main
 @objc class AppDelegate: FlutterAppDelegate {
   override func application(
     _ application: UIApplication,
diff --git a/demos/supabase-todolist/pubspec.lock b/demos/supabase-todolist/pubspec.lock
index 0cd417e9..c873ed38 100644
--- a/demos/supabase-todolist/pubspec.lock
+++ b/demos/supabase-todolist/pubspec.lock
@@ -280,6 +280,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.2.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.1"
   json_annotation:
     dependency: transitive
     description:
@@ -300,18 +308,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -348,18 +356,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   mime:
     dependency: transitive
     description:
@@ -470,21 +478,21 @@ packages:
       path: "../../packages/powersync"
       relative: true
     source: path
-    version: "1.8.8"
+    version: "1.9.0"
   powersync_attachments_helper:
     dependency: "direct main"
     description:
       path: "../../packages/powersync_attachments_helper"
       relative: true
     source: path
-    version: "0.6.12"
+    version: "0.6.14"
   powersync_flutter_libs:
     dependency: "direct overridden"
     description:
       path: "../../packages/powersync_flutter_libs"
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.4.2"
   pub_semver:
     dependency: transitive
     description:
@@ -630,10 +638,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite_async
-      sha256: "1f7b36e6b5b459bae89941ae1d3ae8151a3c14b8242c3b94e75aea4a692361e2"
+      sha256: "4a921c53f12b850c5c7337aa7b2c7a0249efd07696180c1ee6de9750632543c7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.9.1"
+    version: "0.10.1"
   stack_trace:
     dependency: transitive
     description:
@@ -702,10 +710,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   typed_data:
     dependency: transitive
     description:
@@ -806,10 +814,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
   web:
     dependency: transitive
     description:
diff --git a/demos/supabase-todolist/pubspec.yaml b/demos/supabase-todolist/pubspec.yaml
index 3e34efb7..51cbdd37 100644
--- a/demos/supabase-todolist/pubspec.yaml
+++ b/demos/supabase-todolist/pubspec.yaml
@@ -10,8 +10,8 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  powersync_attachments_helper: ^0.6.13
-  powersync: ^1.8.9
+  powersync_attachments_helper: ^0.6.14
+  powersync: ^1.9.0
   path_provider: ^2.1.1
   supabase_flutter: ^2.0.1
   path: ^1.8.3
@@ -19,7 +19,7 @@ dependencies:
   camera: ^0.10.5+7
   image: ^4.1.3
   universal_io: ^2.2.2
-  sqlite_async: ^0.9.0
+  sqlite_async: ^0.10.1
 
 dev_dependencies:
   flutter_test:
diff --git a/packages/powersync/CHANGELOG.md b/packages/powersync/CHANGELOG.md
index e8733016..09dc6824 100644
--- a/packages/powersync/CHANGELOG.md
+++ b/packages/powersync/CHANGELOG.md
@@ -1,6 +1,10 @@
+## 1.9.0
+
+- **FEAT**: Use a sync worker for web that offloads the task of synchronizing databases to a separate worker, allowing it to be coordinated across tabs even when the database itself is not in a shared worker.
+
 ## 1.8.9
 
- - **FIX**: issue where CRUD uploads were not triggered when the SDK reconnected to the PowerSync service after being offline.
+- **FIX**: issue where CRUD uploads were not triggered when the SDK reconnected to the PowerSync service after being offline.
 
 ## 1.8.8
 
diff --git a/packages/powersync/bin/setup_web.dart b/packages/powersync/bin/setup_web.dart
index a18abde1..6d29a6be 100644
--- a/packages/powersync/bin/setup_web.dart
+++ b/packages/powersync/bin/setup_web.dart
@@ -25,6 +25,8 @@ void main(List<String> arguments) async {
   final wasmPath = '${root.toFilePath()}$outputDir/sqlite3.wasm';
 
   final workerPath = '${root.toFilePath()}$outputDir/powersync_db.worker.js';
+  final syncWorkerPath =
+      '${root.toFilePath()}$outputDir/powersync_sync.worker.js';
 
   final packageConfigFile = File.fromUri(
     root.resolve('.dart_tool/package_config.json'),
@@ -57,7 +59,11 @@ void main(List<String> arguments) async {
       final workerUrl =
           'https://github.com/powersync-ja/powersync.dart/releases/download/powersync-v$powersyncVersion/powersync_db.worker.js';
 
+      final syncWorkerUrl =
+          'https://github.com/powersync-ja/powersync.dart/releases/download/powersync-v$powersyncVersion/powersync_sync.worker.js';
+
       await downloadFile(httpClient, workerUrl, workerPath);
+      await downloadFile(httpClient, syncWorkerUrl, syncWorkerPath);
     }
 
     final sqlitePackageName = 'sqlite3';
diff --git a/packages/powersync/lib/src/database/powersync_db_mixin.dart b/packages/powersync/lib/src/database/powersync_db_mixin.dart
index 05e5bae0..af8156e1 100644
--- a/packages/powersync/lib/src/database/powersync_db_mixin.dart
+++ b/packages/powersync/lib/src/database/powersync_db_mixin.dart
@@ -71,11 +71,7 @@ mixin PowerSyncDatabaseMixin implements SqliteConnection {
   @protected
   Future<void> baseInit() async {
     statusStream = statusStreamController.stream;
-    updates = database.updates
-        .map((update) =>
-            PowerSyncUpdateNotification.fromUpdateNotification(update))
-        .where((update) => update.isNotEmpty)
-        .cast<UpdateNotification>();
+    updates = powerSyncUpdateNotifications(database.updates);
 
     await database.initialize();
     await _checkVersion();
@@ -466,3 +462,12 @@ mixin PowerSyncDatabaseMixin implements SqliteConnection {
     await database.refreshSchema();
   }
 }
+
+Stream<UpdateNotification> powerSyncUpdateNotifications(
+    Stream<UpdateNotification> inner) {
+  return inner
+      .map((update) =>
+          PowerSyncUpdateNotification.fromUpdateNotification(update))
+      .where((update) => update.isNotEmpty)
+      .cast<UpdateNotification>();
+}
diff --git a/packages/powersync/lib/src/database/web/web_powersync_database.dart b/packages/powersync/lib/src/database/web/web_powersync_database.dart
index 75809f4e..8b430024 100644
--- a/packages/powersync/lib/src/database/web/web_powersync_database.dart
+++ b/packages/powersync/lib/src/database/web/web_powersync_database.dart
@@ -15,6 +15,8 @@ import 'package:powersync/src/streaming_sync.dart';
 import 'package:sqlite_async/sqlite_async.dart';
 import 'package:powersync/src/schema_logic.dart' as schema_logic;
 
+import '../../web/sync_controller.dart';
+
 /// A PowerSync managed database.
 ///
 /// Web implementation for [PowerSyncDatabase]
@@ -93,7 +95,8 @@ class PowerSyncDatabaseImpl
       Logger? logger}) {
     final db = SqliteDatabase.withFactory(openFactory, maxReaders: 1);
     return PowerSyncDatabaseImpl.withDatabase(
-        schema: schema, logger: logger, database: db);
+        schema: schema, logger: logger, database: db)
+      ..openFactory = openFactory;
   }
 
   /// Open a PowerSyncDatabase on an existing [SqliteDatabase].
@@ -119,14 +122,15 @@ class PowerSyncDatabaseImpl
   /// The connection is automatically re-opened if it fails for any reason.
   ///
   /// Status changes are reported on [statusStream].
-  baseConnect(
-      {required PowerSyncBackendConnector connector,
-
-      /// Throttle time between CRUD operations
-      /// Defaults to 10 milliseconds.
-      required Duration crudThrottleTime,
-      required Future<void> Function() reconnect,
-      Map<String, dynamic>? params}) async {
+  baseConnect({
+    required PowerSyncBackendConnector connector,
+
+    /// Throttle time between CRUD operations
+    /// Defaults to 10 milliseconds.
+    required Duration crudThrottleTime,
+    required Future<void> Function() reconnect,
+    Map<String, dynamic>? params,
+  }) async {
     await initialize();
 
     // Disconnect if connected
@@ -138,9 +142,24 @@ class PowerSyncDatabaseImpl
     final crudStream =
         database.onChange(['ps_crud'], throttle: crudThrottleTime);
 
-    // TODO better multitab support
     final storage = BucketStorage(database);
-    final sync = StreamingSyncImplementation(
+    StreamingSync sync;
+    // Try using a shared worker for the synchronization implementation to avoid
+    // duplicating work across tabs.
+    try {
+      sync = await SyncWorkerHandle.start(
+        this,
+        connector,
+        crudThrottleTime.inMilliseconds,
+        Uri.base.resolve('/powersync_sync.worker.js'),
+      );
+    } catch (e) {
+      logger.warning(
+        'Could not use shared worker for synchronization, falling back to locks.',
+        e,
+      );
+
+      sync = StreamingSyncImplementation(
         adapter: storage,
         credentialsCallback: connector.getCredentialsCached,
         invalidCredentialsCallback: connector.fetchCredentials,
@@ -151,7 +170,10 @@ class PowerSyncDatabaseImpl
         syncParameters: params,
         // Only allows 1 sync implementation to run at a time per database
         // This should be global (across tabs) when using Navigator locks.
-        identifier: database.openFactory.path);
+        identifier: database.openFactory.path,
+      );
+    }
+
     sync.statusStream.listen((event) {
       setStatus(event);
     });
diff --git a/packages/powersync/lib/src/streaming_sync.dart b/packages/powersync/lib/src/streaming_sync.dart
index 57a5ff5b..27c1bd62 100644
--- a/packages/powersync/lib/src/streaming_sync.dart
+++ b/packages/powersync/lib/src/streaming_sync.dart
@@ -19,7 +19,16 @@ import 'sync_types.dart';
 /// a different value to indicate "no error".
 const _noError = Object();
 
-class StreamingSyncImplementation {
+abstract interface class StreamingSync {
+  Stream<SyncStatus> get statusStream;
+
+  Future<void> streamingSync();
+
+  /// Close any active streams.
+  Future<void> abort();
+}
+
+class StreamingSyncImplementation implements StreamingSync {
   BucketStorage adapter;
 
   final Future<PowerSyncCredentials?> Function() credentialsCallback;
@@ -38,6 +47,8 @@ class StreamingSyncImplementation {
 
   final StreamController<SyncStatus> _statusStreamController =
       StreamController<SyncStatus>.broadcast();
+
+  @override
   late final Stream<SyncStatus> statusStream;
 
   late final http.Client _client;
@@ -81,7 +92,7 @@ class StreamingSyncImplementation {
     statusStream = _statusStreamController.stream;
   }
 
-  /// Close any active streams.
+  @override
   Future<void> abort() async {
     // If streamingSync() hasn't been called yet, _abort will be null.
     var future = _abort?.abort();
@@ -117,6 +128,7 @@ class StreamingSyncImplementation {
     return lastStatus.connected;
   }
 
+  @override
   Future<void> streamingSync() async {
     try {
       _abort = AbortController();
diff --git a/packages/powersync/lib/src/version.dart b/packages/powersync/lib/src/version.dart
index 11c304d0..16a94f0e 100644
--- a/packages/powersync/lib/src/version.dart
+++ b/packages/powersync/lib/src/version.dart
@@ -1 +1 @@
-const String libraryVersion = '1.8.9';
+const String libraryVersion = '1.9.0';
diff --git a/packages/powersync/lib/src/web/sync_controller.dart b/packages/powersync/lib/src/web/sync_controller.dart
new file mode 100644
index 00000000..07f5f6b2
--- /dev/null
+++ b/packages/powersync/lib/src/web/sync_controller.dart
@@ -0,0 +1,106 @@
+import 'dart:async';
+import 'dart:js_interop';
+
+import 'package:powersync/powersync.dart';
+import 'package:sqlite_async/web.dart';
+import 'package:web/web.dart';
+
+import '../database/web/web_powersync_database.dart';
+import '../streaming_sync.dart';
+import 'sync_worker_protocol.dart';
+
+class SyncWorkerHandle implements StreamingSync {
+  final PowerSyncDatabaseImpl _database;
+  final PowerSyncBackendConnector _connector;
+  final int _crudThrottleTimeMs;
+
+  late final WorkerCommunicationChannel _channel;
+
+  final StreamController<SyncStatus> _status = StreamController.broadcast();
+
+  SyncWorkerHandle._(this._database, this._connector, this._crudThrottleTimeMs,
+      MessagePort sendToWorker, SharedWorker worker) {
+    _channel = WorkerCommunicationChannel(
+      port: sendToWorker,
+      errors: EventStreamProviders.errorEvent.forTarget(worker),
+      requestHandler: (type, payload) async {
+        switch (type) {
+          case SyncWorkerMessageType.requestEndpoint:
+            final endpoint = await (_database.database as WebSqliteConnection)
+                .exposeEndpoint();
+
+            return (
+              WebEndpoint(
+                databaseName: endpoint.connectName,
+                databasePort: endpoint.connectPort,
+                lockName: endpoint.lockName,
+              ),
+              [endpoint.connectPort].toJS
+            );
+          case SyncWorkerMessageType.uploadCrud:
+            await _connector.uploadData(_database);
+            return (JSObject(), null);
+          case SyncWorkerMessageType.invalidCredentialsCallback:
+            final credentials = await _connector.fetchCredentials();
+            return (
+              credentials != null
+                  ? SerializedCredentials.from(credentials)
+                  : null,
+              null
+            );
+          case SyncWorkerMessageType.credentialsCallback:
+            final credentials = await _connector.getCredentialsCached();
+            return (
+              credentials != null
+                  ? SerializedCredentials.from(credentials)
+                  : null,
+              null
+            );
+          default:
+            throw StateError('Unexpected message type $type');
+        }
+      },
+    );
+
+    _channel.events.listen((data) {
+      final (type, payload) = data;
+      if (type == SyncWorkerMessageType.notifySyncStatus) {
+        _status.add((payload as SerializedSyncStatus).asSyncStatus());
+      }
+    });
+  }
+
+  static Future<SyncWorkerHandle> start(
+      PowerSyncDatabaseImpl database,
+      PowerSyncBackendConnector connector,
+      int crudThrottleTimeMs,
+      Uri workerUri) async {
+    final worker = SharedWorker(workerUri.toString().toJS);
+    final handle = SyncWorkerHandle._(
+        database, connector, crudThrottleTimeMs, worker.port, worker);
+
+    // Make sure that the worker is working, or throw immediately.
+    await handle._channel.ping();
+
+    return handle;
+  }
+
+  Future<void> close() async {
+    await abort();
+    await _channel.close();
+  }
+
+  @override
+  Future<void> abort() async {
+    await _channel.abortSynchronization();
+  }
+
+  @override
+  Stream<SyncStatus> get statusStream => _status.stream;
+
+  @override
+  Future<void> streamingSync() async {
+    await _channel.startSynchronization(
+        _database.openFactory.path, _crudThrottleTimeMs);
+  }
+}
diff --git a/packages/powersync/lib/src/web/sync_worker.dart b/packages/powersync/lib/src/web/sync_worker.dart
new file mode 100644
index 00000000..040f979b
--- /dev/null
+++ b/packages/powersync/lib/src/web/sync_worker.dart
@@ -0,0 +1,274 @@
+/// This file needs to be compiled to JavaScript with the command
+/// dart compile js -O4 packages/powersync/lib/src/web/sync_worker.dart -o assets/powersync_sync.worker.js
+/// The output should then be included in each project's `web` directory
+library;
+
+import 'dart:async';
+import 'dart:js_interop';
+
+import 'package:async/async.dart';
+import 'package:fetch_client/fetch_client.dart';
+import 'package:powersync/powersync.dart';
+import 'package:powersync/sqlite_async.dart';
+import 'package:powersync/src/database/powersync_db_mixin.dart';
+import 'package:powersync/src/streaming_sync.dart';
+import 'package:sqlite_async/web.dart';
+import 'package:web/web.dart' hide RequestMode;
+
+import '../bucket_storage.dart';
+import 'sync_worker_protocol.dart';
+
+final _logger = autoLogger;
+
+void main() {
+  _SyncWorker().start();
+}
+
+class _SyncWorker {
+  final SharedWorkerGlobalScope _self;
+  final Map<String, _SyncRunner> _requestedSyncTasks = {};
+
+  _SyncWorker() : _self = globalContext as SharedWorkerGlobalScope;
+
+  void start() async {
+    // Start listening for connect events, each signifies a client connecting
+    // to this worker.
+    EventStreamProviders.connectEvent.forTarget(_self).listen((e) {
+      final ports = (e as MessageEvent).ports.toDart;
+      for (final port in ports) {
+        _ConnectedClient(port, this);
+      }
+    });
+  }
+
+  _SyncRunner referenceSyncTask(String databaseIdentifier,
+      int crudThrottleTimeMs, _ConnectedClient client) {
+    return _requestedSyncTasks.putIfAbsent(databaseIdentifier, () {
+      return _SyncRunner(databaseIdentifier, crudThrottleTimeMs);
+    })
+      ..registerClient(client);
+  }
+}
+
+class _ConnectedClient {
+  late WorkerCommunicationChannel channel;
+  final _SyncWorker _worker;
+
+  _SyncRunner? _runner;
+  StreamSubscription? _logSubscription;
+
+  _ConnectedClient(MessagePort port, this._worker) {
+    channel = WorkerCommunicationChannel(
+      port: port,
+      requestHandler: (type, payload) async {
+        switch (type) {
+          case SyncWorkerMessageType.startSynchronization:
+            final request = payload as StartSynchronization;
+            _runner = _worker.referenceSyncTask(
+                request.databaseName, request.crudThrottleTimeMs, this);
+            return (JSObject(), null);
+          case SyncWorkerMessageType.abortSynchronization:
+            _runner?.unregisterClient(this);
+            _runner = null;
+            return (JSObject(), null);
+          default:
+            throw StateError('Unexpected message type $type');
+        }
+      },
+    );
+
+    _logSubscription = _logger.onRecord.listen((record) {
+      final msg = StringBuffer(
+          '[${record.loggerName}] ${record.level.name}: ${record.time}: ${record.message}');
+
+      if (record.error != null) {
+        msg
+          ..writeln()
+          ..write(record.error);
+      }
+      if (record.stackTrace != null) {
+        msg
+          ..writeln()
+          ..write(record.stackTrace);
+      }
+
+      channel.notify(SyncWorkerMessageType.logEvent, msg.toString().toJS);
+    });
+  }
+
+  void markClosed() {
+    _logSubscription?.cancel();
+    _runner?.unregisterClient(this);
+    _runner = null;
+  }
+}
+
+class _SyncRunner {
+  final String identifier;
+  final int crudThrottleTimeMs;
+
+  final StreamGroup<_RunnerEvent> _group = StreamGroup();
+  final StreamController<_RunnerEvent> _mainEvents = StreamController();
+
+  StreamingSync? sync;
+  _ConnectedClient? databaseHost;
+  final connections = <_ConnectedClient>[];
+
+  _SyncRunner(this.identifier, this.crudThrottleTimeMs) {
+    _group.add(_mainEvents.stream);
+
+    Future(() async {
+      await for (final event in _group.stream) {
+        try {
+          switch (event) {
+            case _AddConnection(:final client):
+              connections.add(client);
+              if (sync == null) {
+                await _requestDatabase(client);
+              }
+            case _RemoveConnection(:final client):
+              connections.remove(client);
+              if (connections.isEmpty) {
+                await sync?.abort();
+                sync = null;
+              }
+            case _ActiveDatabaseClosed():
+              _logger.info('Remote database closed, finding a new client');
+              sync?.abort();
+              sync = null;
+
+              // The only reliable notification we get for a client closing is
+              // when that client is currently hosting the database. Use the
+              // opportunity to check whether secondary clients have also closed
+              // in the meantime.
+              final newHost = await _collectActiveClients();
+              if (newHost == null) {
+                _logger.info('No client remains');
+              } else {
+                await _requestDatabase(newHost);
+              }
+          }
+        } catch (e, s) {
+          _logger.warning('Error handling $event', e, s);
+        }
+      }
+    });
+  }
+
+  /// Pings all current [connections], removing those that don't answer in 5s
+  /// (as they are likely closed tabs as well).
+  ///
+  /// Returns the first client that responds (without waiting for others).
+  Future<_ConnectedClient?> _collectActiveClients() async {
+    final candidates = connections.toList();
+    if (candidates.isEmpty) {
+      return null;
+    }
+
+    final firstResponder = Completer<_ConnectedClient?>();
+    var pendingRequests = candidates.length;
+
+    for (final candidate in candidates) {
+      candidate.channel.ping().then((_) {
+        pendingRequests--;
+        if (!firstResponder.isCompleted) {
+          firstResponder.complete(candidate);
+        }
+      }).timeout(const Duration(seconds: 5), onTimeout: () {
+        pendingRequests--;
+        candidate.markClosed();
+        if (pendingRequests == 0 && !firstResponder.isCompleted) {
+          // All requests have timed out, no connection remains
+          firstResponder.complete(null);
+        }
+      });
+    }
+
+    return firstResponder.future;
+  }
+
+  Future<void> _requestDatabase(_ConnectedClient client) async {
+    _logger.info('Sync setup: Requesting database');
+
+    // This is the first client, ask for a database connection
+    final connection = await client.channel.requestDatabase();
+    _logger.info('Sync setup: Connecting to endpoint');
+    final database = await WebSqliteConnection.connectToEndpoint((
+      connectPort: connection.databasePort,
+      connectName: connection.databaseName,
+      lockName: connection.lockName,
+    ));
+    _logger.info('Sync setup: Has database, starting sync!');
+    databaseHost = client;
+
+    database.closedFuture.then((_) {
+      _logger.fine('Detected closed client');
+      client.markClosed();
+
+      if (client == databaseHost) {
+        _logger
+            .info('Tab providing sync database has gone down, reconnecting...');
+        _mainEvents.add(const _ActiveDatabaseClosed());
+      }
+    });
+
+    final tables = ['ps_crud'];
+    final crudThrottleTime = Duration(milliseconds: crudThrottleTimeMs);
+    Stream<UpdateNotification> crudStream =
+        powerSyncUpdateNotifications(Stream.empty());
+    if (database.updates != null) {
+      final filteredStream = database.updates!
+          .transform(UpdateNotification.filterTablesTransformer(tables));
+      crudStream = UpdateNotification.throttleStream(
+        filteredStream,
+        crudThrottleTime,
+        addOne: UpdateNotification.empty(),
+      );
+    }
+
+    sync = StreamingSyncImplementation(
+      adapter: BucketStorage(database),
+      credentialsCallback: client.channel.credentialsCallback,
+      invalidCredentialsCallback: client.channel.invalidCredentialsCallback,
+      uploadCrud: client.channel.uploadCrud,
+      crudUpdateTriggerStream: crudStream,
+      retryDelay: Duration(seconds: 3),
+      client: FetchClient(mode: RequestMode.cors),
+      identifier: identifier,
+    );
+    sync!.statusStream.listen((event) {
+      _logger.fine('Broadcasting sync event: $event');
+      for (final client in connections) {
+        client.channel.notify(SyncWorkerMessageType.notifySyncStatus,
+            SerializedSyncStatus.from(event));
+      }
+    });
+    sync!.streamingSync();
+  }
+
+  void registerClient(_ConnectedClient client) {
+    _mainEvents.add(_AddConnection(client));
+  }
+
+  void unregisterClient(_ConnectedClient client) {
+    _mainEvents.add(_RemoveConnection(client));
+  }
+}
+
+sealed class _RunnerEvent {}
+
+final class _AddConnection implements _RunnerEvent {
+  final _ConnectedClient client;
+
+  _AddConnection(this.client);
+}
+
+final class _RemoveConnection implements _RunnerEvent {
+  final _ConnectedClient client;
+
+  _RemoveConnection(this.client);
+}
+
+final class _ActiveDatabaseClosed implements _RunnerEvent {
+  const _ActiveDatabaseClosed();
+}
diff --git a/packages/powersync/lib/src/web/sync_worker_protocol.dart b/packages/powersync/lib/src/web/sync_worker_protocol.dart
new file mode 100644
index 00000000..1e01fabf
--- /dev/null
+++ b/packages/powersync/lib/src/web/sync_worker_protocol.dart
@@ -0,0 +1,365 @@
+import 'dart:async';
+import 'dart:js_interop';
+
+import 'package:web/web.dart';
+
+import '../connector.dart';
+import '../log.dart';
+import '../sync_status.dart';
+
+/// Names used in [SyncWorkerMessage]
+enum SyncWorkerMessageType {
+  ping,
+
+  /// Sent from client to the sync worker to request the synchronization
+  /// starting.
+  startSynchronization,
+
+  /// Te [SyncWorkerMessage.payload] for the request is a numeric id, the
+  /// response can be anything (void).
+  abortSynchronization,
+
+  /// Sent from the sync worker to the client when it needs an endpoint to
+  /// connect to to start the synchronization.
+  ///
+  /// [SyncWorkerMessage.payload] is a numeric request id, the response sends
+  /// a [WebEndpoint].
+  requestEndpoint,
+
+  /// Invoke the `uploadCrud`, `fetchCredentials` and `getCredentialsCached`
+  /// methods on the client.
+  ///
+  /// For requests, the [SyncWorkerMessage.payload] is a numeric request id.
+  /// The response sends either a [SerializedCredentials] object or an empty
+  /// object for uploads.
+  uploadCrud,
+  invalidCredentialsCallback,
+  credentialsCallback,
+
+  /// Notifies clients that the sync status has changed - the payload consists
+  /// of [SerializedSyncStatus].
+  notifySyncStatus,
+
+  /// Notifies clients about a log event emitted by the worker (typically only
+  /// used when workers were compiled in debug mode).
+  /// The payload is a [JSString].
+  logEvent,
+
+  okResponse,
+  errorResponse,
+}
+
+@anonymous
+extension type SyncWorkerMessage._(JSObject _) implements JSObject {
+  external factory SyncWorkerMessage(
+      {required String type, required JSAny payload});
+
+  external String get type;
+  external JSAny get payload;
+}
+
+@anonymous
+extension type StartSynchronization._(JSObject _) implements JSObject {
+  external factory StartSynchronization({
+    required String databaseName,
+    required int crudThrottleTimeMs,
+    required int requestId,
+  });
+
+  external String get databaseName;
+  external int get requestId;
+  external int get crudThrottleTimeMs;
+}
+
+@anonymous
+extension type WebEndpoint._(JSObject _) implements JSObject {
+  external factory WebEndpoint({
+    required String databaseName,
+    required MessagePort databasePort,
+    required String? lockName,
+  });
+
+  external String get databaseName;
+  external String? get lockName;
+  external MessagePort get databasePort;
+}
+
+@anonymous
+extension type OkResponse._(JSObject _) implements JSObject {
+  external factory OkResponse({
+    required int requestId,
+    required JSAny? payload,
+  });
+
+  external int get requestId;
+  external JSAny? get payload;
+}
+
+@anonymous
+extension type ErrorResponse._(JSObject _) implements JSObject {
+  external factory ErrorResponse({
+    required int requestId,
+    required JSString errorMessage,
+  });
+
+  external int get requestId;
+  external JSString get errorMessage;
+}
+
+@anonymous
+extension type SerializedCredentials._(JSObject _) implements JSObject {
+  external factory SerializedCredentials({
+    required JSString endpoint,
+    required JSString token,
+    required JSString? userId,
+    required JSNumber? expiresAt,
+  });
+
+  factory SerializedCredentials.from(PowerSyncCredentials credentials) {
+    return SerializedCredentials(
+      endpoint: credentials.endpoint.toJS,
+      token: credentials.token.toJS,
+      userId: credentials.userId?.toJS,
+      expiresAt: credentials.expiresAt?.microsecondsSinceEpoch.toJS,
+    );
+  }
+
+  external JSString get endpoint;
+  external JSString get token;
+  external JSString? get userId;
+  external JSNumber? get expiresAt;
+
+  PowerSyncCredentials asCredentials() {
+    return PowerSyncCredentials(
+      endpoint: endpoint.toDart,
+      token: token.toDart,
+      userId: userId?.toDart,
+      expiresAt: expiresAt.isUndefinedOrNull
+          ? null
+          : DateTime.fromMicrosecondsSinceEpoch(expiresAt!.toDartInt),
+    );
+  }
+}
+
+@anonymous
+extension type SerializedSyncStatus._(JSObject _) implements JSObject {
+  external factory SerializedSyncStatus({
+    required bool connected,
+    required bool connecting,
+    required bool downloading,
+    required bool uploading,
+    required int? lastSyncedAt,
+    required bool? hasSyned,
+    required String? uploadError,
+    required String? downloadError,
+  });
+
+  factory SerializedSyncStatus.from(SyncStatus status) {
+    return SerializedSyncStatus(
+      connected: status.connected,
+      connecting: status.connecting,
+      downloading: status.downloading,
+      uploading: status.uploading,
+      lastSyncedAt: status.lastSyncedAt?.microsecondsSinceEpoch,
+      hasSyned: status.hasSynced,
+      uploadError: status.uploadError?.toString(),
+      downloadError: status.downloadError?.toString(),
+    );
+  }
+
+  external bool get connected;
+  external bool get connecting;
+  external bool get downloading;
+  external bool get uploading;
+  external int? lastSyncedAt;
+  external bool? hasSynced;
+  external String? uploadError;
+  external String? downloadError;
+
+  SyncStatus asSyncStatus() {
+    return SyncStatus(
+      connected: connected,
+      connecting: connecting,
+      downloading: downloading,
+      uploading: uploading,
+      lastSyncedAt: lastSyncedAt == null
+          ? null
+          : DateTime.fromMicrosecondsSinceEpoch(lastSyncedAt!),
+      hasSynced: hasSynced,
+      uploadError: uploadError,
+      downloadError: downloadError,
+    );
+  }
+}
+
+final class WorkerCommunicationChannel {
+  static final _logger = autoLogger;
+
+  final Map<int, Completer<JSAny?>> _pendingRequests = {};
+  int _nextRequestId = 0;
+  bool _hasError = false;
+  StreamSubscription? _incomingMessages;
+  StreamSubscription? _incomingErrors;
+
+  final MessagePort port;
+  final FutureOr<(JSAny?, JSArray?)> Function(SyncWorkerMessageType, JSAny)
+      requestHandler;
+  final StreamController<(SyncWorkerMessageType, JSAny)> _events =
+      StreamController();
+
+  Stream<(SyncWorkerMessageType, JSAny)> get events => _events.stream;
+
+  WorkerCommunicationChannel({
+    required this.port,
+    required this.requestHandler,
+    Stream<Event>? errors,
+  }) {
+    port.start();
+    _incomingErrors = errors?.listen((event) {
+      _hasError = true;
+
+      _pendingRequests.forEach((_, value) {
+        value.completeError('Worker error: $event');
+      });
+      _pendingRequests.clear();
+    });
+
+    _incomingMessages =
+        EventStreamProviders.messageEvent.forTarget(port).listen((event) async {
+      final message = event.data as SyncWorkerMessage;
+      final type = SyncWorkerMessageType.values.byName(message.type);
+      _logger.fine('[in] $type');
+
+      int requestId;
+
+      switch (type) {
+        case SyncWorkerMessageType.ping:
+          requestId = (message.payload as JSNumber).toDartInt;
+          port.postMessage(SyncWorkerMessage(
+            type: SyncWorkerMessageType.okResponse.name,
+            payload: OkResponse(requestId: requestId, payload: null),
+          ));
+          return;
+        case SyncWorkerMessageType.startSynchronization:
+          requestId = (message.payload as StartSynchronization).requestId;
+        case SyncWorkerMessageType.requestEndpoint:
+        case SyncWorkerMessageType.abortSynchronization:
+        case SyncWorkerMessageType.credentialsCallback:
+        case SyncWorkerMessageType.invalidCredentialsCallback:
+        case SyncWorkerMessageType.uploadCrud:
+          requestId = (message.payload as JSNumber).toDartInt;
+        case SyncWorkerMessageType.okResponse:
+          final payload = message.payload as OkResponse;
+          _pendingRequests.remove(payload.requestId)!.complete(payload.payload);
+          return;
+        case SyncWorkerMessageType.errorResponse:
+          final payload = message.payload as ErrorResponse;
+          _pendingRequests
+              .remove(payload.requestId)!
+              .completeError(payload.errorMessage.toDart);
+          return;
+        case SyncWorkerMessageType.notifySyncStatus:
+          _events.add((type, message.payload));
+          return;
+        case SyncWorkerMessageType.logEvent:
+          final msg = (message.payload as JSString).toDart;
+          _logger.info('[Sync Worker]: $msg');
+          return;
+      }
+
+      try {
+        final (response, transfer) =
+            await requestHandler(type, message.payload);
+        final responseMessage = SyncWorkerMessage(
+          type: SyncWorkerMessageType.okResponse.name,
+          payload: OkResponse(requestId: requestId, payload: response),
+        );
+
+        if (transfer != null) {
+          port.postMessage(responseMessage, transfer);
+        } else {
+          port.postMessage(responseMessage);
+        }
+      } catch (e) {
+        port.postMessage(SyncWorkerMessage(
+          type: SyncWorkerMessageType.errorResponse.name,
+          payload: ErrorResponse(
+              requestId: requestId, errorMessage: e.toString().toJS),
+        ));
+      }
+    });
+  }
+
+  (int, Future<JSAny?>) _newRequest() {
+    if (_hasError) {
+      throw StateError('Channel has error, cannot send new requests');
+    }
+
+    final id = _nextRequestId++;
+    final completer = _pendingRequests[id] = Completer<JSAny?>.sync();
+    return (id, completer.future);
+  }
+
+  Future<JSAny?> _numericRequest(SyncWorkerMessageType type) {
+    final (id, future) = _newRequest();
+    port.postMessage(SyncWorkerMessage(type: type.name, payload: id.toJS));
+    return future;
+  }
+
+  void notify(SyncWorkerMessageType notificationType, JSAny payload) {
+    port.postMessage(
+        SyncWorkerMessage(type: notificationType.name, payload: payload));
+  }
+
+  Future<void> ping() async {
+    await _numericRequest(SyncWorkerMessageType.ping);
+  }
+
+  Future<void> startSynchronization(
+      String databaseName, int crudThrottleTimeMs) async {
+    final (id, completion) = _newRequest();
+    port.postMessage(SyncWorkerMessage(
+      type: SyncWorkerMessageType.startSynchronization.name,
+      payload: StartSynchronization(
+          databaseName: databaseName,
+          crudThrottleTimeMs: crudThrottleTimeMs,
+          requestId: id),
+    ));
+    await completion;
+  }
+
+  Future<void> abortSynchronization() async {
+    await _numericRequest(SyncWorkerMessageType.abortSynchronization);
+  }
+
+  // Called by the sync worker to request a [WebEndpoint] for the database
+  // managed by the client.
+  Future<WebEndpoint> requestDatabase() async {
+    return await _numericRequest(SyncWorkerMessageType.requestEndpoint)
+        as WebEndpoint;
+  }
+
+  Future<PowerSyncCredentials?> credentialsCallback() async {
+    final serialized =
+        await _numericRequest(SyncWorkerMessageType.credentialsCallback)
+            as SerializedCredentials?;
+    return serialized?.asCredentials();
+  }
+
+  Future<PowerSyncCredentials?> invalidCredentialsCallback() async {
+    final serialized =
+        await _numericRequest(SyncWorkerMessageType.invalidCredentialsCallback)
+            as SerializedCredentials?;
+    return serialized?.asCredentials();
+  }
+
+  Future<void> uploadCrud() async {
+    await _numericRequest(SyncWorkerMessageType.uploadCrud);
+  }
+
+  Future<void> close() async {
+    _incomingMessages?.cancel();
+    _incomingErrors?.cancel();
+    port.close();
+  }
+}
diff --git a/packages/powersync/pubspec.yaml b/packages/powersync/pubspec.yaml
index 1cb800d9..03879eb9 100644
--- a/packages/powersync/pubspec.yaml
+++ b/packages/powersync/pubspec.yaml
@@ -1,5 +1,5 @@
 name: powersync
-version: 1.8.9
+version: 1.9.0
 homepage: https://powersync.com
 repository: https://github.com/powersync-ja/powersync.dart
 description: PowerSync Flutter SDK - sync engine for building local-first apps.
@@ -10,7 +10,7 @@ dependencies:
   flutter:
     sdk: flutter
 
-  sqlite_async: ^0.9.1
+  sqlite_async: ^0.10.1
   # We only use sqlite3 as a transitive dependency,
   # but right now we need a minimum of v2.4.6.
   sqlite3: ^2.4.6
@@ -27,6 +27,8 @@ dependencies:
   pubspec_parse: ^1.3.0
   args: ^2.5.0
   pub_semver: ^2.1.4
+  js: ^0.7.0
+  web: ^1.0.0
 dev_dependencies:
   dcli: ^4.0.0
   lints: ^3.0.0
@@ -38,7 +40,6 @@ dev_dependencies:
   shelf_static: ^1.1.2
   stream_channel: ^2.1.2
   path: ^1.8.3
-  js: ">=0.6.7 <0.8.0"
 
 platforms:
   android:
diff --git a/packages/powersync_attachments_helper/CHANGELOG.md b/packages/powersync_attachments_helper/CHANGELOG.md
index fd46da63..2249066a 100644
--- a/packages/powersync_attachments_helper/CHANGELOG.md
+++ b/packages/powersync_attachments_helper/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.6.14
+
+ - Update a dependency to the latest release.
+
 ## 0.6.13
 
  - Update a dependency to the latest release.
diff --git a/packages/powersync_attachments_helper/pubspec.yaml b/packages/powersync_attachments_helper/pubspec.yaml
index e38e05c5..8711e118 100644
--- a/packages/powersync_attachments_helper/pubspec.yaml
+++ b/packages/powersync_attachments_helper/pubspec.yaml
@@ -1,6 +1,6 @@
 name: powersync_attachments_helper
 description: A helper library for handling attachments when using PowerSync.
-version: 0.6.13
+version: 0.6.14
 repository: https://github.com/powersync-ja/powersync.dart
 homepage: https://www.powersync.com/
 environment:
@@ -10,9 +10,9 @@ dependencies:
   flutter:
     sdk: flutter
 
-  powersync: ^1.8.9
+  powersync: ^1.9.0
   logging: ^1.2.0
-  sqlite_async: ^0.9.1
+  sqlite_async: ^0.10.1
   path_provider: ^2.0.13
 
 dev_dependencies:
diff --git a/scripts/compile_webworker.dart b/scripts/compile_webworker.dart
index 3233d2be..7520fe2b 100644
--- a/scripts/compile_webworker.dart
+++ b/scripts/compile_webworker.dart
@@ -9,27 +9,52 @@ Future<void> main() async {
 
   /// The monorepo root assets directory
   final workerFilename = 'powersync_db.worker.js';
-  final outputPath =
+  final dbWorkerOutputPath =
       path.join(repoRoot, 'packages/powersync/assets/$workerFilename');
 
   final workerSourcePath = path.join(
       repoRoot, './packages/powersync/lib/src/web/powersync_db.worker.dart');
 
   // And compile worker code
-  final process = await Process.run(
+  final dbWorkerProcess = await Process.run(
       Platform.executable,
       [
         'compile',
         'js',
         '-o',
-        outputPath,
+        dbWorkerOutputPath,
         '-O4',
         workerSourcePath,
       ],
       workingDirectory: cwd);
 
-  if (process.exitCode != 0) {
-    throw Exception('Could not compile worker: ${process.stdout.toString()}');
+  if (dbWorkerProcess.exitCode != 0) {
+    throw Exception(
+        'Could not compile db worker: ${dbWorkerProcess.stdout.toString()}');
+  }
+
+  final syncWorkerFilename = 'powersync_sync.worker.js';
+  final syncWorkerOutputPath =
+      path.join(repoRoot, 'packages/powersync/assets/$syncWorkerFilename');
+
+  final syncWorkerSourcePath =
+      path.join(repoRoot, './packages/powersync/lib/src/web/sync_worker.dart');
+
+  final syncWorkerProcess = await Process.run(
+      Platform.executable,
+      [
+        'compile',
+        'js',
+        '-o',
+        syncWorkerOutputPath,
+        '-O4',
+        syncWorkerSourcePath,
+      ],
+      workingDirectory: cwd);
+
+  if (syncWorkerProcess.exitCode != 0) {
+    throw Exception(
+        'Could not compile sync worker: ${dbWorkerProcess.stdout.toString()}');
   }
 
   // Copy this to all demo apps web folders
@@ -44,6 +69,8 @@ Future<void> main() async {
       continue;
     }
     final demoOutputPath = path.join(demoWebDir, workerFilename);
-    File(outputPath).copySync(demoOutputPath);
+    File(dbWorkerOutputPath).copySync(demoOutputPath);
+    File(syncWorkerOutputPath)
+        .copySync(path.join(demoWebDir, syncWorkerFilename));
   }
 }