Firebase | emulate

Emulated Firebase Auth (Identity Toolkit + Secure Token) and FCM v1 for local development and testing.

A stateful emulator for Firebase Authentication and Cloud Messaging.

Included now:

Identity Toolkit REST: signUp, signInWithPassword, lookup, update, delete, sendOobCode
Secure Token: refresh ID tokens (POST /v1/token)
FCM v1: POST /v1/projects/<projectId>/messages:send

Start

# From this repo (after `bun install && bun run build`)
bun packages/emulate/dist/index.js --service firebase

# Or from the published package
npx @pleaseai/emulate --service firebase

A single service starts on the base port (default 4000). Use -p <port> to change it. When started alongside other services, ports are assigned sequentially from the base port (firebase’s slot is 4003).

Point a Firebase SDK at the emulator with FIREBASE_AUTH_EMULATOR_HOST=localhost:4000.

Auth

Identity Toolkit and Secure Token take the API key as a query param: ?key=<api_key>.
FCM messages:send requires Authorization: Bearer <token> (presence only — the token is not cryptographically verified).

The googleapis.com-prefixed path variants are also accepted, e.g. /identitytoolkit.googleapis.com/v1/accounts:signUp and /securetoken.googleapis.com/v1/token.

Flow

# 1. Sign up with email + password
curl -X POST "http://localhost:4000/v1/accounts:signUp?key=firebase_api_key_example" \
  -H "Content-Type: application/json" \
  -d '{"email":"hong@example.com","password":"password123","returnSecureToken":true}'
# → {"idToken":"...","refreshToken":"...","expiresIn":"3600","localId":"..."}

# 2. Sign in with email + password
curl -X POST "http://localhost:4000/v1/accounts:signInWithPassword?key=firebase_api_key_example" \
  -H "Content-Type: application/json" \
  -d '{"email":"hong@example.com","password":"password123","returnSecureToken":true}'

# 3. Refresh the ID token
curl -X POST "http://localhost:4000/v1/token?key=firebase_api_key_example" \
  -H "Content-Type: application/json" \
  -d '{"grant_type":"refresh_token","refresh_token":"<refreshToken>"}'

# 4. Send an FCM message
curl -X POST "http://localhost:4000/v1/projects/demo-project/messages:send" \
  -H "Authorization: Bearer test-token" \
  -H "Content-Type: application/json" \
  -d '{"message":{"token":"<device_token>","notification":{"title":"Hi","body":"World"}}}'

Inspect emulator state (no auth) at GET /internal/messages and GET /internal/oob_codes.

Seed Config

Add a firebase: section to emulate.config.yaml (or pass --seed <file>):

firebase:
  projects:
    - project_id: demo-project
      api_key: firebase_api_key_example
  users:
    - email: hong@example.com
      password: password123
      display_name: 홍길동