Vercel Labs Emulate

Local servers act like real APIs for Vercel, GitHub, and Google. They work without any network connection. This is great for running tests in a CI pipeline or inside a sandbox. The servers use real in-memory state, not simple mocks. They support pagination, OAuth, webhooks, and cascading deletes. You can start them from the command line or use them in code with Vitest or Jest. No network needed for testing.

You can seed the servers with custom data using a YAML config file. Each API runs on its own port and can be reset to a clean state between tests. The emulator is a drop-in replacement that behaves like the real services. Developers benefit from faster and more reliable tests without depending on live APIs.

This tool is designed for teams that need production-fidelity local testing. It replaces network calls with a local server that handles all the same logic. The result is a smooth testing experience without timeout or rate limit issues.