API Faker

> Get a full fake REST API with zero coding in less than 30 seconds (seriously)

Created with ❤️ for front-end developers who need a quick back-end for prototyping and mocking.

![Tests]()
![TypeScript]()
![License]()

Table of Contents

- Features
- Installation
- Getting Started
- Usage
- CLI Options
- Routes
- Query Parameters
- Relationships
- Configuration
- Custom Routes & Middlewares
- Examples
- Programmatic Usage
- Development
- License

Features

- ✨ Zero coding required - Start with a JSON file
- 🚀 Quick setup - Get an API running in < 30 seconds
- 🔄 Full REST API - Complete CRUD operations (GET, POST, PUT, PATCH, DELETE)
- 🔍 Advanced filtering - Filter by any property, use operators like \_gte, \_lte, \_like
- 📊 Sorting & Pagination - Sort by multiple fields, paginate with \_page and \_limit
- 🔗 Relationships - Embed child resources and expand parent resources
- 📁 Static file serving - Serve your HTML, CSS, and JS files
- 🎨 URL rewriting - Create custom routes and aliases
- 🔧 Highly customizable - CLI options and config file support
- 💾 Auto-save - Changes are automatically saved to your data file
- 🌐 CORS enabled - Ready for cross-origin requests
- ⚡ Fast & lightweight - Built with Express and TypeScript
- 🧪 Well tested - 214 tests with comprehensive coverage

Installation

``bash


NPM

npm install -g rest_api_faker

Yarn

yarn global add rest_api_faker

PNPM

pnpm add -g rest_api_faker
`

Getting Started

1. Create a db.json file:

`json
{
"posts": [
{ "id": 1, "title": "Hello World", "author": "John Doe" },
{ "id": 2, "title": "API Faker is awesome", "author": "Jane Smith" }
],
"comments": [
{ "id": 1, "body": "Great post!", "postId": 1 },
{ "id": 2, "body": "Thanks for sharing", "postId": 1 }
],
"profile": {
"name": "John Doe",
"email": "john@example.com"
}
}
`

2. Start the server:

`bash
rest_api_faker db.json
`

Or with watch mode to auto-reload on file changes:

`bash
rest_api_faker --watch db.json
`

Note: Watch mode monitors your data file, routes file, and middlewares file for changes and automatically reloads them.

3. Access your API:

`bash


Get all posts

curl http://localhost:3000/posts

Get a single post

curl http://localhost:3000/posts/1

Get profile

curl http://localhost:3000/profile
`

That's it! 🎉 You now have a fully functional REST API.

Usage

$3

`bash
rest_api_faker [options]

Options:
-c, --config Path to config file (default: "rest_api_faker.json")
-p, --port Set port (default: 3000)
-H, --host Set host (default: "localhost")
-w, --watch Watch data, routes, and middlewares files for changes
-r, --routes Path to routes file (URL rewrite rules)
-m, --middlewares Path to middleware file
-s, --static Set static files directory (default: "./public")
--no-static Disable static file serving
--ro, --read-only Allow only GET requests
--nc, --no-cors Disable Cross-Origin Resource Sharing
--ng, --no-gzip Disable GZIP Content-Encoding
-S, --snapshots Set snapshots directory (default: ".")
-d, --delay Add delay to responses (ms)
-i, --id Set database id property (default: "id")
--fks Set foreign key suffix (default: "Id")
-q, --quiet Suppress log messages
-l, --log-level Set log level: trace | debug | info (default: "info")
-h, --help Show help
-v, --version Show version number

Log Levels:
trace Show all logs including trace messages (most verbose)
debug Show debug and info logs (hide trace)
info Show only info logs (default, least verbose)

Examples:
rest_api_faker db.json Start with db.json
rest_api_faker --watch db.json Start with auto-reload
rest_api_faker --port 4000 db.json Start on port 4000
rest_api_faker file.js Use a JavaScript file
rest_api_faker --routes routes.json Use custom routes
rest_api_faker --log-level debug db.json Show debug logs
rest_api_faker --log-level trace db.json Show all logs including trace
`

$3

Based on your db.json, API Faker automatically creates the following routes:

#### Plural Resources

`
GET /posts # List all posts
GET /posts/1 # Get post with id=1
POST /posts # Create a new post
PUT /posts/1 # Replace post with id=1
PATCH /posts/1 # Update post with id=1
DELETE /posts/1 # Delete post with id=1
`

#### Singular Resources

`
GET /profile # Get profile
POST /profile # Create/replace profile
PUT /profile # Replace profile
PATCH /profile # Update profile
`

#### Special Routes

`
GET /db # Get the full database
GET / # Homepage (serves index.html or shows available routes)
`

$3

#### Filtering

Filter by any property:

`bash


Posts with specific title

GET /posts?title=Hello World

Multiple values (OR)

GET /posts?id=1&id=2

Deep property access

GET /posts?author.name=John
`

#### Pagination

`bash


Get page 2 with 10 items per page

GET /posts?_page=2&_limit=10

Default limit is 10

GET /posts?_page=1
`

Returns Link header with first, prev, next, and last links.

#### Sorting

`bash


Sort by title (ascending)

GET /posts?_sort=title

Sort by title (descending)

GET /posts?_sort=title&_order=desc

Sort by multiple fields

GET /posts?_sort=author,title&_order=desc,asc
`

#### Slicing

`bash


Get items 20-30

GET /posts?_start=20&_end=30

Get 10 items starting from 20

GET /posts?_start=20&_limit=10
`

Returns X-Total-Count header with the total number of items.

#### Operators

`bash


Greater than or equal

GET /posts?views_gte=1000

Less than or equal

GET /posts?views_lte=100

Not equal

GET /posts?author_ne=John

Like (supports RegExp)

GET /posts?title_like=server
`

#### Full-Text Search

`bash


Search across all string fields


GET /posts?q=awesome
`

$3

#### Embed Children

Use _embed to include child resources (based on foreign keys):

`bash


Get post with embedded comments

GET /posts/1?_embed=comments

Result:

{
"id": 1,
"title": "Hello World",
"comments": [
{ "id": 1, "body": "Great post!", "postId": 1 }
]
}
`

#### Expand Parent

Use _expand to include parent resource:

`bash


Get comment with expanded post

GET /comments/1?_expand=post

Result:

{
"id": 1,
"body": "Great post!",
"postId": 1,
"post": { "id": 1, "title": "Hello World" }
}
`

#### Nested Routes

`bash


Get all comments for post 1

GET /posts/1/comments

Create a comment for post 1

POST /posts/1/comments
{
"body": "New comment"
}

postId will be automatically set to 1

`

Configuration

You can use a configuration file instead of CLI options. Create an rest_api_faker.json file:

`json
{
"port": 3000,
"host": "localhost",
"watch": true,
"routes": "routes.json",
"middlewares": "middleware.js",
"static": "./public",
"readOnly": false,
"noCors": false,
"noGzip": false,
"delay": 0,
"id": "id",
"foreignKeySuffix": "Id",
"quiet": false,
"logLevel": "info"
}
`

Configuration Options:

- port - Server port (default: 3000)
- host - Server host (default: "localhost")
- watch - Watch for file changes (default: false)
- routes - Path to routes file for URL rewriting
- middlewares - Path to custom middleware file
- static - Static files directory (default: "./public")
- readOnly - Allow only GET requests (default: false)
- noCors - Disable CORS (default: false)
- noGzip - Disable GZIP compression (default: false)
- delay - Add delay to responses in milliseconds
- id - Database ID field name (default: "id")
- foreignKeySuffix - Foreign key suffix (default: "Id")
- quiet - Suppress log messages (default: false)
- logLevel - Log level: "trace" | "debug" | "info" (default: "info")

Then simply run:

`bash
rest_api_faker db.json
`

Using a custom config file:

`bash
rest_api_faker db.json --config my-config.json
`

Note: CLI arguments override config file values.

Custom Routes & Middlewares

$3

Create a routes.json file with URL rewrite rules:

`json
{
"/api/*": "/$1",
"/:resource/:id/show": "/:resource/:id",
"/posts/:category": "/posts?category=:category",
"/me": "/profile"
}
`

Use it:

`bash
rest_api_faker db.json --routes routes.json
`

Now you can access:

- /api/posts → /posts
- /posts/1/show → /posts/1
- /posts/tech → /posts?category=tech
- /me → /profile

$3

Create a middleware.js file:

`javascript
module.exports = function (req, res, next) {
// Add custom header
res.setHeader('X-Custom-API', 'API Faker');

// Log request
console.log(${req.method} ${req.url});

// Continue
next();
};
`

Use it:

`bash
rest_api_faker db.json --middlewares middleware.js
`

See examples/README.md for more examples.

Examples

$3

`bash


Start with default settings

rest_api_faker db.json

Start with watch mode

rest_api_faker --watch db.json

Start on a different port

rest_api_faker --port 4000 db.json

Read-only mode (only GET requests)

rest_api_faker --read-only db.json

Add delay to all responses (useful for testing loading states)

rest_api_faker --delay 1000 db.json
`

$3

Create a db.js file:

`javascript
module.exports = function () {
const data = {
users: [],
posts: [],
};

// Generate 100 users
for (let i = 1; i <= 100; i++) {
data.users.push({
id: i,
name: User ${i},
email: user${i}@example.com,
});
}

// Generate 500 posts
for (let i = 1; i <= 500; i++) {
data.posts.push({
id: i,
title: Post ${i},
userId: Math.ceil(Math.random() * 100),
});
}

return data;
};
`

Start the server:

`bash
rest_api_faker db.js
`

Tip: Use libraries like Faker.js for more realistic data.

$3

Create an authentication middleware:

`javascript
// auth-middleware.js
module.exports = function (req, res, next) {
// Allow all GET requests
if (req.method === 'GET') {
return next();
}

// Check for authorization token
const token = req.headers.authorization;

if (!token || token !== 'Bearer secret-token') {
return res.status(401).json({
error: 'Unauthorized',
message: 'Please provide a valid authorization token',
});
}

next();
};
`

Use it:

`bash
rest_api_faker db.json --middlewares auth-middleware.js
`

Now all POST, PUT, PATCH, DELETE requests require the Authorization: Bearer secret-token header.

$3

Vercel:

Create a vercel.json:

`json
{
"version": 2,
"builds": [
{
"src": "server.js",
"use": "@vercel/node"
}
],
"routes": [
{
"src": "/(.*)",
"dest": "server.js"
}
]
}
`

Create a server.js:

`javascript
const jsonServer = require('rest_api_faker');
const server = jsonServer.create();
const router = jsonServer.router('db.json');
const middlewares = jsonServer.defaults();

server.use(middlewares);
server.use(router);

module.exports = server;
`

Deploy:

`bash
vercel
`

Heroku:

Create a Procfile:

`
web: node server.js
`

Create a server.js:

`javascript
const jsonServer = require('rest_api_faker');
const server = jsonServer.create();
const router = jsonServer.router('db.json');
const middlewares = jsonServer.defaults();

const port = process.env.PORT || 3000;

server.use(middlewares);
server.use(router);
server.listen(port, () => {
console.log(API Faker is running on port ${port});
});
`

Deploy:

`bash
git init
git add .
git commit -m "Initial commit"
heroku create
git push heroku main
`

Programmatic Usage

You can also use API Faker programmatically in your Node.js applications:

`javascript
const jsonServer = require('rest_api_faker');
const server = jsonServer.create();
const router = jsonServer.router('db.json');
const middlewares = jsonServer.defaults();

server.use(middlewares);
server.use(router);

server.listen(3000, () => {
console.log('API Faker is running');
});
`

Note: Full programmatic API is coming in a future release.

Development

`bash


Install dependencies

pnpm install

Run in development mode

pnpm dev

Build

pnpm build

Run tests

pnpm test

Run tests with coverage

pnpm test:coverage

Type check

pnpm typecheck

Lint

pnpm lint

Format code

pnpm format
``

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT © 2026

Acknowledgments

Inspired by json-server by typicode.

---

Happy Mocking! 🚀