vercel

Vercel API Emulator

Fully stateful Vercel REST API emulation with Vercel-style JSON responses and cursor-based pagination.

Start

Local listeners bind to 127.0.0.1 by default. For access from containers or other machines, pass --host 0.0.0.0 to the CLI or hostname: '0.0.0.0' to createEmulator. Configure --base-url or baseUrl for advertised URLs reachable by those clients.

# Vercel only
npx emulate --service vercel

# Default port
# http://localhost:4000

Or programmatically:

import { createEmulator } from 'emulate'

const vercel = await createEmulator({ service: 'vercel', port: 4000 })
// vercel.url === 'http://localhost:4000'

Auth

Pass tokens as Authorization: Bearer <token>. All endpoints accept teamId or slug query params for team scoping.

curl http://localhost:4000/v2/user \
  -H "Authorization: Bearer test_token_admin"

Team-scoped requests resolve the account from the teamId or slug query parameter. User-scoped requests resolve the account from the authenticated user.

Pointing Your App at the Emulator

Environment Variable

VERCEL_EMULATOR_URL=http://localhost:4000

Vercel SDK / Custom Fetch

const VERCEL_API = process.env.VERCEL_EMULATOR_URL ?? 'https://api.vercel.com'

const res = await fetch(`${VERCEL_API}/v10/projects`, {
  headers: { Authorization: `Bearer ${token}` },
})

OAuth URL Mapping

Real Vercel URL	Emulator URL
https://vercel.com/integrations/oauth/authorize	$VERCEL_EMULATOR_URL/oauth/authorize
https://api.vercel.com/login/oauth/token	$VERCEL_EMULATOR_URL/login/oauth/token
https://api.vercel.com/login/oauth/userinfo	$VERCEL_EMULATOR_URL/login/oauth/userinfo

Auth.js / NextAuth.js

{
  id: 'vercel',
  name: 'Vercel',
  type: 'oauth',
  authorization: {
    url: `${process.env.VERCEL_EMULATOR_URL}/oauth/authorize`,
  },
  token: {
    url: `${process.env.VERCEL_EMULATOR_URL}/login/oauth/token`,
  },
  userinfo: {
    url: `${process.env.VERCEL_EMULATOR_URL}/login/oauth/userinfo`,
  },
  clientId: process.env.VERCEL_CLIENT_ID,
  clientSecret: process.env.VERCEL_CLIENT_SECRET,
  profile(profile) {
    return {
      id: profile.sub,
      name: profile.name,
      email: profile.email,
      image: profile.picture,
    }
  },
}