# Vercel Emulator (service host)

Create an instance:
curl -s -X POST https://vercel.emulators.dev/_emulate/instances
# Hosted deployments create instances lazily when the returned URL is first used. The instance URL is a capability: anyone who has it can read and modify the instance, so save the returned URLs. Never store real secrets in an emulator.
# The server generates an unguessable name. An optional {"instance":"<prefix>"} body adds a readable prefix.

Then use the returned providerBaseUrl / controlBaseUrl. Example below uses a sample instance.
# Vercel Emulator

Stateful Vercel API emulator for projects, deployments, domains, teams, users, env vars, and integration OAuth flows.

Provider base URL: https://vercel.your-instance.emulators.dev
Control base URL: https://vercel.your-instance.emulators.dev/_emulate

Supported surfaces:
- REST API: partial at /
- Integration OAuth: supported at /oauth

Control endpoints:
- https://vercel.your-instance.emulators.dev/_emulate/manifest
- https://vercel.your-instance.emulators.dev/_emulate/coverage
- https://vercel.your-instance.emulators.dev/_emulate/connections
- https://vercel.your-instance.emulators.dev/_emulate/state
- https://vercel.your-instance.emulators.dev/_emulate/ledger
- https://vercel.your-instance.emulators.dev/_emulate/faults
- POST https://vercel.your-instance.emulators.dev/_emulate/credentials
- POST https://vercel.your-instance.emulators.dev/_emulate/seed
- POST https://vercel.your-instance.emulators.dev/_emulate/reset

Fault injection:
Arm a one-shot provider failure with a glob pathPattern, then inspect /ledger for faulted: true.
curl -s -X POST https://vercel.your-instance.emulators.dev/_emulate/faults \
  -H "content-type: application/json" \
  -d '{"match":{"method":"GET","pathPattern":"/v1/*"},"response":{"status":503,"body":{"error":"temporary"}}}'

Connect:

## Vercel SDK (TypeScript)
import { Vercel } from "@vercel/sdk";

const vercel = new Vercel({
  serverURL: "https://vercel.your-instance.emulators.dev",
  bearerToken: "<token>",
});

const { projects } = await vercel.projects.getProjects({});

## fetch (TypeScript)
const res = await fetch("https://vercel.your-instance.emulators.dev/v2/user", {
  headers: { authorization: "Bearer <token>" },
});
const { user } = await res.json();

## Vercel API base URL (env)
VERCEL_API_URL=https://vercel.your-instance.emulators.dev
VERCEL_TOKEN=<token>

## curl
curl -s https://vercel.your-instance.emulators.dev/v2/user -H "authorization: Bearer <token>"

## Base URL (env)
VERCEL_BASE_URL=https://vercel.your-instance.emulators.dev

## Create a credential
curl -s -X POST https://vercel.your-instance.emulators.dev/_emulate/credentials \
  -H "content-type: application/json" \
  -d '{"type":"bearer-token"}'

## Inspect requests
curl -s https://vercel.your-instance.emulators.dev/_emulate/ledger