mock-api-server

Zero-dependency CLI to spin up a mock REST API server instantly from a JSON config file. Perfect for frontend development and testing.

Install

npm install -g mock-api-server

Or run without installing:

npx mock-api-server --init
npx mock-api-server mock-api.json

Quick start

# 1. Create a sample config
mock-api --init

# 2. Start the server
mock-api mock-api.json

# Output:
#   mock-api running on http://localhost:3000
#   GET     /users → 200
#   POST    /users → 201
#   GET     /users/:id → 200
#   ...

Config format

Create a mock-api.json file:

{
  "GET /users": {
    "status": 200,
    "body": [
      { "id": 1, "name": "Alice" },
      { "id": 2, "name": "Bob" }
    ]
  },
  "GET /users/:id": {
    "status": 200,
    "body": { "id": "{id}", "name": "Alice" }
  },
  "POST /users": {
    "status": 201,
    "body": { "message": "User created", "id": 3 }
  },
  "DELETE /users/:id": {
    "status": 204,
    "body": {}
  }
}

URL parameters

Use {param} in response body to echo back URL params:

"GET /users/:id": {
  "status": 200,
  "body": { "id": "{id}", "name": "Alice" }
}

GET /users/42 → { "id": "42", "name": "Alice" }

Options

| Flag | Description | Default | |------|-------------|---------| | --port=N | Port to listen on | 3000 | | --delay=N | Add N ms delay to responses | 0 | | --quiet | Suppress request logs | off | | --init | Create a sample mock-api.json | — | | --help | Show help | — |

Features

• ✅ URL params (:id, :slug, etc.)
• ✅ All HTTP methods (GET, POST, PUT, PATCH, DELETE)
• ✅ CORS headers — works with any frontend out of the box
• ✅ Simulated delay with --delay
• ✅ Custom status codes per route
• ✅ Zero dependencies — pure Node.js

Running tests

npm test

License

MIT