[Workers] Multi Workers development

src/content/docs/workers/development-testing/multi-workers.mdx

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+---
+pcx_content_type: concept
+title: Developing with multiple Workers
+sidebar:
+  order: 3
+head: []
+description: Learn how to develop with multiple Workers using different approaches and configurations.
+---
+
+import { Aside, PackageManagers, Steps, WranglerConfig } from "~/components";
+
+When building complex applications, you may want to run multiple Workers during development. This guide covers the different approaches for running multiple Workers locally and when to use each approach.
+
+## Single dev command
+
+<Aside type="tip">
+
+We recommend this approach as the default for most development workflows as it ensures the best compatibility with bindings.
+
+</Aside>
+
+You can run multiple Workers in a single dev command by passing multiple configuration files to your dev server:
+
+**Using Wrangler**
+
+<PackageManagers
+  type="exec"
+  pkg="wrangler"
+  args="dev -c ./app/wrangler.jsonc -c ./api/wrangler.jsonc"
+/>
+
+The first config (`./app/wrangler.jsonc`) is treated as the primary Worker, exposed at `http://localhost:8787`. Additional configs (e.g. `./api/wrangler.jsonc`) run as auxiliary Workers, available via service bindings or tail consumers from the primary Worker.
+
+**Using the Vite plugin**
+
+Configure `auxiliaryWorkers` in your Vite configuration:
+
+```js title="vite.config.js"
+import { defineConfig } from "vite";
+import { cloudflare } from "@cloudflare/vite-plugin";
+
+export default defineConfig({
+  plugins: [
+    cloudflare({
+      configPath: "./app/wrangler.jsonc",
+      auxiliaryWorkers: [
+        {
+          configPath: "./api/wrangler.jsonc",
+        },
+      ],
+    }),
+  ],
+});
+```
+
+Then run:
+
+<PackageManagers type="exec" pkg="vite" args="dev" />
+
+**Use this approach when:**
+
+- You want the simplest setup for development
+- Workers are part of the same application or codebase
+- You need to access a Durable Object namespace from another Worker using `script_name`, or setup Queues where the producer and consumer Workers are seperated.
+
+## Multiple dev commands
+
+You can also run each Worker in a separate dev commands, each with its own terminal and configuration.
+
+<PackageManagers
+  comment="Terminal 1"
+  type="exec"
+  pkg="wrangler"
+  args="dev -c ./app/wrangler.jsonc"
+/>
+
+<PackageManagers
+  comment="Terminal 2"
+  type="exec"
+  pkg="wrangler"
+  args="dev -c ./api/wrangler.jsonc"
+/>
+
+These Workers run in different dev commands but can still communicate with each other via service bindings or tail consumers **regardless of whether they are started with `wrangler dev` or `vite dev`**.
+
+<Aside type="note">
+
+You can also combine both approaches — for example, run a group of Workers together through `vite dev` using `auxiliaryWorkers`, while running another Worker separately with `wrangler dev`. This allows you to keep tightly coupled Workers running under a single dev command, while keeping independent or shared Workers in separate ones. However, 
+running `wrangler dev` with multiple configuration files (e.g. `wrangler dev -c ./app/wrangler.jsonc -c ./api/wrangler.jsonc`) does **not** support cross-process bindings at the moment.
+
+</Aside>
+
+**Use this approach when:**
+
+- You want each Worker to be accessible on its own local URL during development, since only the primary Worker is exposed when using a single dev command
+- Each Worker has its own build setup or tooling — for example, one uses Vite with custom plugins while another is a vanilla Wrangler project
+- You need the flexibility to run and develop Workers independently without restructuring your project or consolidating configs
+
+This setup is especially useful in larger projects where each team maintains a subset of Workers. Running everything in a single dev command might require significant restructuring or build integration that isn't always practical.