Skill

apple

Name: apple
Author: Vercel Labs

emulate Apple Sign-in for local development

Published by Vercel Labs Updated Jul 17

Covers Auth Local Development Apple Testing

Description

Emulated Sign in with Apple / Apple OIDC for local development and testing. Use when the user needs to test Apple sign-in locally, emulate Apple OIDC discovery, handle Apple token exchange, configure Apple OAuth clients, or work with Apple userinfo without hitting real Apple APIs. Triggers include "Apple OAuth", "emulate Apple", "mock Apple login", "test Apple sign-in", "Sign in with Apple", "Apple OIDC", "local Apple auth", or any task requiring a local Apple OAuth/OIDC provider.

SKILL.md

Start

# Apple only
npx emulate --service apple

# Default port (when run alone)
# http://localhost:4000

Or programmatically:

import { createEmulator } from 'emulate'

const apple = await createEmulator({ service: 'apple', port: 4004 })
// apple.url === 'http://localhost:4004'

Pointing Your App at the Emulator

Environment Variable

APPLE_EMULATOR_URL=http://localhost:4004

OAuth URL Mapping

Real Apple URL	Emulator URL
`https://appleid.apple.com/.well-known/openid-configuration`	`$APPLE_EMULATOR_URL/.well-known/openid-configuration`
`https://appleid.apple.com/auth/authorize`	`$APPLE_EMULATOR_URL/auth/authorize`
`https://appleid.apple.com/auth/token`	`$APPLE_EMULATOR_URL/auth/token`
`https://appleid.apple.com/auth/keys`	`$APPLE_EMULATOR_URL/auth/keys`
`https://appleid.apple.com/auth/revoke`	`$APPLE_EMULATOR_URL/auth/revoke`

Auth.js / NextAuth.js

import Apple from '@auth/core/providers/apple'

Apple({
  clientId: process.env.APPLE_CLIENT_ID,
  clientSecret: process.env.APPLE_CLIENT_SECRET,
  authorization: {
    url: `${process.env.APPLE_EMULATOR_URL}/auth/authorize`,
    params: { scope: 'openid email name', response_mode: 'form_post' },
  },
  token: {
    url: `${process.env.APPLE_EMULATOR_URL}/auth/token`,
  },
  jwks_endpoint: `${process.env.APPLE_EMULATOR_URL}/auth/keys`,
})

Passport.js

import { Strategy as AppleStrategy } from 'passport-apple'

const APPLE_URL = process.env.APPLE_EMULATOR_URL ?? 'https://appleid.apple.com'

new AppleStrategy({
  clientID: process.env.APPLE_CLIENT_ID,
  teamID: process.env.APPLE_TEAM_ID,
  keyID: process.env.APPLE_KEY_ID,
  callbackURL: 'http://localhost:3000/api/auth/callback/apple',
  authorizationURL: `${APPLE_URL}/auth/authorize`,
  tokenURL: `${APPLE_URL}/auth/token`,
}, verifyCallback)

Seed Config

apple:
  users:
    - email: testuser@icloud.com
      name: Test User
      given_name: Test
      family_name: User
    - email: private@example.com
      name: Private User
      is_private_email: true
  oauth_clients:
    - client_id: com.example.app
      team_id: TEAM001
      name: My Apple App
      redirect_uris:
        - http://localhost:3000/api/auth/callback/apple

When no OAuth clients are configured, the emulator accepts any client_id. With clients configured, strict validation is enforced for client_id and redirect_uri.

Users with is_private_email: true get a generated @privaterelay.appleid.com email in the id_token instead of their real email.

API Endpoints

OIDC Discovery

curl http://localhost:4004/.well-known/openid-configuration

Returns the standard OIDC discovery document with all endpoints pointing to the emulator:

{
  "issuer": "http://localhost:4004",
  "authorization_endpoint": "http://localhost:4004/auth/authorize",
  "token_endpoint": "http://localhost:4004/auth/token",
  "jwks_uri": "http://localhost:4004/auth/keys",
  "revocation_endpoint": "http://localhost:4004/auth/revoke",
  "response_types_supported": ["code"],
  "subject_types_supported": ["pairwise"],
  "id_token_signing_alg_values_supported": ["RS256"],
  "scopes_supported": ["openid", "email", "name"],
  "token_endpoint_auth_methods_supported": ["client_secret_post"],
  "response_modes_supported": ["query", "fragment", "form_post"]
}

JWKS

curl http://localhost:4004/auth/keys

Returns an RSA public key (kid: emulate-apple-1) for verifying id_token signatures.

Authorization

# Browser flow: redirects to a user picker page
curl -v "http://localhost:4004/auth/authorize?\
client_id=com.example.app&\
redirect_uri=http://localhost:3000/api/auth/callback/apple&\
scope=openid+email+name&\
response_type=code&\
state=random-state&\
nonce=random-nonce&\
response_mode=form_post"

Query parameters:

Param	Description
`client_id`	OAuth client ID (Apple Services ID)
`redirect_uri`	Callback URL
`scope`	Space-separated scopes (`openid email name`)
`state`	Opaque state for CSRF protection
`nonce`	Nonce for ID token (optional)
`response_mode`	`query` (default), `form_post`, or `fragment`

The emulator renders an HTML page where you select a seeded user. After selection, it redirects (or auto-submits a form for form_post) to redirect_uri with code and state. On the first authorization per user/client pair, a user JSON blob is also included (matching Apple's real behavior).

Token Exchange

curl -X POST http://localhost:4004/auth/token \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "code=<authorization_code>&\
client_id=com.example.app&\
client_secret=<client_secret>&\
grant_type=authorization_code"

Returns:

{
  "access_token": "apple_...",
  "refresh_token": "r_apple_...",
  "id_token": "<jwt>",
  "token_type": "Bearer",
  "expires_in": 3600
}

The id_token is an RS256 JWT containing sub, email, email_verified (string), is_private_email (string), real_user_status, auth_time, and optional nonce.

Refresh Token

curl -X POST http://localhost:4004/auth/token \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "refresh_token=r_apple_...&\
client_id=com.example.app&\
grant_type=refresh_token"

Returns a new access_token and id_token. No new refresh_token is issued on refresh (matching Apple's behavior).

Token Revocation

curl -X POST http://localhost:4004/auth/revoke \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "token=apple_..."

Returns 200 OK. The token is removed from the emulator's token map.

Common Patterns

Full Authorization Code Flow

APPLE_URL="http://localhost:4004"
CLIENT_ID="com.example.app"
REDIRECT_URI="http://localhost:3000/api/auth/callback/apple"

# 1. Open in browser (user picks a seeded account)
#    $APPLE_URL/auth/authorize?client_id=$CLIENT_ID&redirect_uri=$REDIRECT_URI&scope=openid+email+name&response_type=code&state=abc&response_mode=form_post

# 2. After user selection, emulator posts to:
#    $REDIRECT_URI with code=<code>&state=abc (and user JSON on first auth)

# 3. Exchange code for tokens
curl -X POST $APPLE_URL/auth/token \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "code=<code>&client_id=$CLIENT_ID&grant_type=authorization_code"

# 4. Decode the id_token JWT to get user info

Private Relay Email

When a user has is_private_email: true in the seed config, the id_token will contain a generated @privaterelay.appleid.com email instead of the user's real email. This matches Apple's Hide My Email behavior.

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