diff --git a/firestore-stripe-web-sdk/package.json b/firestore-stripe-web-sdk/package.json
index c5bed58a..b31e062a 100644
--- a/firestore-stripe-web-sdk/package.json
+++ b/firestore-stripe-web-sdk/package.json
@@ -3,6 +3,7 @@
   "version": "0.0.7",
   "description": "Client SDK for the firestore-stripe-payments Firebase Extension",
   "main": "./lib/index.js",
+  "type": "module",
   "typings": "./lib/index.d.ts",
   "scripts": {
     "api-documenter": "api-documenter markdown --input-folder temp --output-folder markdown",
diff --git a/firestore-stripe-web-sdk/src/index.ts b/firestore-stripe-web-sdk/src/index.ts
index 5ad1b28d..7126782e 100644
--- a/firestore-stripe-web-sdk/src/index.ts
+++ b/firestore-stripe-web-sdk/src/index.ts
@@ -20,7 +20,7 @@ export {
   StripePaymentsErrorCode,
   StripePaymentsOptions,
   getStripePayments,
-} from "./init";
+} from "./init.js";
 
 export {
   CREATE_SESSION_TIMEOUT_MILLIS,
@@ -36,7 +36,7 @@ export {
   PriceIdSessionCreateParams,
   Session,
   SessionCreateParams,
-} from "./session";
+} from "./session.js";
 
 export {
   GetPaymentsOptions,
@@ -47,7 +47,7 @@ export {
   getCurrentUserPayment,
   getCurrentUserPayments,
   onCurrentUserPaymentUpdate,
-} from "./payment";
+} from "./payment.js";
 
 export {
   GetProductOptions,
@@ -60,7 +60,7 @@ export {
   getPrices,
   getProduct,
   getProducts,
-} from "./product";
+} from "./product.js";
 
 export {
   getCurrentUserSubscription,
@@ -71,4 +71,4 @@ export {
   SubscriptionChangeType,
   SubscriptionSnapshot,
   SubscriptionStatus,
-} from "./subscription";
+} from "./subscription.js";
diff --git a/firestore-stripe-web-sdk/src/payment.ts b/firestore-stripe-web-sdk/src/payment.ts
index 108774d9..d28c19d5 100644
--- a/firestore-stripe-web-sdk/src/payment.ts
+++ b/firestore-stripe-web-sdk/src/payment.ts
@@ -36,9 +36,9 @@ import {
   QuerySnapshot,
   where,
 } from "@firebase/firestore";
-import { StripePayments, StripePaymentsError } from "./init";
-import { getCurrentUser, getCurrentUserSync } from "./user";
-import { checkNonEmptyArray, checkNonEmptyString } from "./utils";
+import { StripePayments, StripePaymentsError } from "./init.js";
+import { getCurrentUser, getCurrentUserSync } from "./user.js";
+import { checkNonEmptyArray, checkNonEmptyString } from "./utils.js";
 
 /**
  * Interface of a Stripe payment stored in the app database.
diff --git a/firestore-stripe-web-sdk/src/product.ts b/firestore-stripe-web-sdk/src/product.ts
index 1ce3fa37..37045e0a 100644
--- a/firestore-stripe-web-sdk/src/product.ts
+++ b/firestore-stripe-web-sdk/src/product.ts
@@ -36,8 +36,8 @@ import {
   where,
   WhereFilterOp,
 } from "@firebase/firestore";
-import { StripePayments, StripePaymentsError } from "./init";
-import { checkNonEmptyString } from "./utils";
+import { StripePayments, StripePaymentsError } from "./init.js";
+import { checkNonEmptyString } from "./utils.js";
 
 /**
  * Interface of a Stripe Product stored in the app database.
diff --git a/firestore-stripe-web-sdk/src/session.ts b/firestore-stripe-web-sdk/src/session.ts
index decbc1d4..ad86b7e5 100644
--- a/firestore-stripe-web-sdk/src/session.ts
+++ b/firestore-stripe-web-sdk/src/session.ts
@@ -31,13 +31,13 @@ import {
   Timestamp,
   Unsubscribe,
 } from "@firebase/firestore";
-import { StripePayments, StripePaymentsError } from "./init";
-import { getCurrentUser } from "./user";
+import { StripePayments, StripePaymentsError } from "./init.js";
+import { getCurrentUser } from "./user.js";
 import {
   checkNonEmptyArray,
   checkNonEmptyString,
   checkPositiveNumber,
-} from "./utils";
+} from "./utils.js";
 
 /**
  * Parameters common across all session types.
diff --git a/firestore-stripe-web-sdk/src/subscription.ts b/firestore-stripe-web-sdk/src/subscription.ts
index 09115667..35bd66c4 100644
--- a/firestore-stripe-web-sdk/src/subscription.ts
+++ b/firestore-stripe-web-sdk/src/subscription.ts
@@ -37,9 +37,9 @@ import {
   Timestamp,
   where,
 } from "@firebase/firestore";
-import { StripePayments, StripePaymentsError } from "./init";
-import { getCurrentUser, getCurrentUserSync } from "./user";
-import { checkNonEmptyArray, checkNonEmptyString } from "./utils";
+import { StripePayments, StripePaymentsError } from "./init.js";
+import { getCurrentUser, getCurrentUserSync } from "./user.js";
+import { checkNonEmptyArray, checkNonEmptyString } from "./utils.js";
 
 /**
  * Interface of a Stripe Subscription stored in the app database.
diff --git a/firestore-stripe-web-sdk/src/user.ts b/firestore-stripe-web-sdk/src/user.ts
index c3203858..1f992428 100644
--- a/firestore-stripe-web-sdk/src/user.ts
+++ b/firestore-stripe-web-sdk/src/user.ts
@@ -16,7 +16,7 @@
 
 import { FirebaseApp } from "@firebase/app";
 import { Auth, getAuth } from "@firebase/auth";
-import { StripePayments, StripePaymentsError } from "./init";
+import { StripePayments, StripePaymentsError } from "./init.js";
 
 /**
  * Internal API for retrieving the currently signed in user. Rejects with "unauthenticated" if