> ## Documentation Index
> Fetch the complete documentation index at: https://docs.launchtoday.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Google Sign-In

> Configure Google Sign-In for the Launch mobile app

## Overview

This guide walks you through creating Google OAuth credentials and connecting
them to the Launch mobile app. The boilerplate uses Expo AuthSession in
`apps/mobile/lib/auth/google.ts` and sends the Google token to the API for
verification. These steps work for both iOS and Android in the Launch template.

## Prerequisites

* Access to Google Cloud Console
* A Google Cloud project created for your app

<Tip>
  Start with [Backend Authentication Setup](/authentication/backend-setup) so
  your API and env file are in place.
</Tip>

## Steps

## Step 1: Create your OAuth client ID (iOS)

Open [Google Cloud Console](https://console.cloud.google.com/), then go to
**APIs & Services** → **Credentials** and click **Create credentials** →
**OAuth client ID**.

If Google prompts you to configure the **OAuth consent screen** first, complete
that setup before continuing. Choose **External**, enter your app name, support
email, and developer contact email, then add yourself as a test user. Save the
changes and return to the **Credentials** page.

Now create an **iOS** OAuth client. Give it a name, then enter the iOS bundle
identifier from `apps/mobile/app.config.ts`. After you create the client, copy
the iOS client ID—you will use it in your mobile environment file.

## Step 2: Create a Web client ID (required)

The shared Google Auth module validates both an iOS client ID and a Web client
ID, even when you are testing mobile locally. Create a **Web application**
OAuth client and use your ngrok HTTPS URL for both the origin and redirect.

Set these values in the Web client configuration (replace with your ngrok
forwarding URL):

* **Authorized JavaScript origins**: `https://YOUR_NGROK_ID.ngrok-free.app`
* **Authorized redirect URIs**: `https://YOUR_NGROK_ID.ngrok-free.app/api/auth/callback/google`

These should match the ngrok URL you set in your backend and mobile env files
so the OAuth flow stays on a single origin.

## Step 3: Update environment files

Update `apps/mobile/.env` with:

* `EXPO_PUBLIC_GOOGLE_IOS_CLIENT_ID`
* `EXPO_PUBLIC_GOOGLE_WEB_CLIENT_ID`

Update `apps/api/.env` with:

* `GOOGLE_WEB_CLIENT_ID`
* `GOOGLE_CLIENT_SECRET`

Restart the API after changing backend values. For the mobile app, stop your dev
server and run `pnpm ios` or `pnpm android` again so the updated env values are
bundled into the development build. You only need to run `pnpm prebuild` again
if you changed native config in `apps/mobile/app.config.ts` (for example, URL
schemes).

## Step 4: Enable iOS deep links

Update `apps/mobile/app.config.ts` to enable the iOS URL scheme used by Google
Sign-In. Set the `CFBundleURLName` to a readable app name, and set the
`CFBundleURLSchemes` value to the **iOS URL scheme** shown in Google Cloud
Console for the iOS client you created in Step 1.

If these values are currently commented out, uncomment them and replace the
placeholders.

When you set `CFBundleURLName`, it is safest to use the same value as your
bundle identifier (for example, `com.company.launchstarter`) so it stays
consistent with the rest of your iOS configuration.

## Step 5: Test the sign-in flow

Open the app, tap Google Sign-In, and complete the consent flow. You should be
redirected back into the app and see an authenticated session.