Serves JSON files through REST routes with authentication.
Last updated 2 months ago by iamsuman .
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Inspired and Forked from JSON Server

Get a full fake REST API with authorization.

Getting started

Install HAI Server

npm install -g hai-server

Create a db.json file with some data

  "posts": [
    { "id": 1, "title": "hai-server", "author": "sumn2u" }
  "comments": [
    { "id": 1, "body": "some comment", "postId": 1 }
  "profile": { "name": "sumn2u" }

Start HAI Server

hai-server --watch db.json

Now if you go to http://localhost:3000/posts/1, you'll get

{ "id": 1, "title": "hai-server", "author": "sumn2u" }

Also when doing requests, it's good to know that:

  • If you make POST, PUT, PATCH or DELETE requests, changes will be automatically and safely saved to db.json using lowdb.
  • Your request body JSON should be object enclosed, just like the GET output. (for example {"name": "Foobar"})
  • Id values are not mutable. Any id value in the body of your PUT or PATCH request will be ignored. Only a value set in a POST request will be respected, but only if not already taken.
  • A POST, PUT or PATCH request should include a Content-Type: application/json header to use the JSON in the request body. Otherwise it will result in a 200 OK but without changes being made to the data.


Based on the previous db.json file, here are all the default routes. You can also add other routes using --routes.

Plural routes

GET    /posts
GET    /posts/1
POST   /posts
PUT    /posts/1
PATCH  /posts/1
DELETE /posts/1

Singular routes

GET    /profile
POST   /profile
PUT    /profile
PATCH  /profile


Use . to access deep properties

GET /posts?title=hai-server&author=sumn2u
GET /posts?id=1&id=2
GET /comments?author.name=sumn2u


Use _page and optionally _limit to paginate returned data.

In the Link header you'll get first, prev, next and last links.

GET /posts?_page=7
GET /posts?_page=7&_limit=20

10 items are returned by default


Add _sort and _order (ascending order by default)

GET /posts?_sort=views&_order=asc
GET /posts/1/comments?_sort=votes&_order=asc

For multiple fields, use the following format:

GET /posts?_sort=user,views&_order=desc,asc


Add _start and _end or _limit (an X-Total-Count header is included in the response)

GET /posts?_start=20&_end=30
GET /posts/1/comments?_start=20&_end=30
GET /posts/1/comments?_start=20&_limit=10

Works exactly as Array.slice (i.e. _start is inclusive and _end exclusive)


Add _gte or _lte for getting a range

GET /posts?views_gte=10&views_lte=20

Add _ne to exclude a value

GET /posts?id_ne=1

Add _like to filter (RegExp supported)

GET /posts?title_like=server

Full-text search

Add q

GET /posts?q=internet


To include children resources, add _embed

GET /posts?_embed=comments
GET /posts/1?_embed=comments

To include parent resource, add _expand

GET /comments?_expand=post
GET /comments/1?_expand=post

To get or create nested resources (by default one level, add custom routes for more)

GET  /posts/1/comments
POST /posts/1/comments


GET /db


Returns default index file or serves ./public directory



Static file server

You can use HAI Server to serve your HTML, JS and CSS, simply create a ./public directory or use --static to set a different static files directory.

mkdir public
echo 'hello world' > public/index.html
hai-server db.json
hai-server db.json --static ./some-other-dir

Alternative port

You can start HAI Server on other ports with the --port flag:

$ hai-server --watch db.json --port 3004

Access from anywhere

You can access your fake API from anywhere using CORS and JSONP.

Remote schema

You can load remote schemas.

$ hai-server http://example.com/file.json
$ hai-server http://jsonplaceholder.sumn2u.com/db

Generate random data

Using JS instead of a JSON file, you can create data programmatically.

// index.js
module.exports = () => {
  const data = { users: [] }
  // Create 1000 users
  for (let i = 0; i < 1000; i++) {
    data.users.push({ id: i, name: `user${i}` })
  return data
$ hai-server index.js

Tip use modules like Faker, Casual, Chance or JSON Schema Faker.


There are many ways to set up SSL in development. One simple way is to use hotel.

Add custom routes

Create a routes.json file. Pay attention to start every route with /.

  "/api/*": "/$1",
  "/:resource/:id/show": "/:resource/:id",
  "/posts/:category": "/posts?category=:category",
  "/articles\\?id=:id": "/posts/:id"

Start HAI Server with --routes option.

hai-server db.json --routes routes.json

Now you can access resources using additional routes.

/api/posts # → /posts
/api/posts/1  # → /posts/1
/posts/1/show # → /posts/1
/posts/javascript # → /posts?category=javascript
/articles?id=1 # → /posts/1

Add middlewares

You can add your middlewares from the CLI using --middlewares option:

// hello.js
module.exports = (req, res, next) => {
  res.header('X-Hello', 'World')
hai-server db.json --middlewares ./hello.js
hai-server db.json --middlewares ./first.js ./second.js

CLI usage

hai-server [options] <source>

  --config, -c       Path to config file           [default: "hai-server.json"]
  --port, -p         Set port                                    [default: 3000]
  --host, -H         Set host                             [default: "localhost"]
  --watch, -w        Watch file(s)                                     [boolean]
  --routes, -r       Path to routes file
  --middlewares, -m  Paths to middleware files                           [array]
  -- auth, -a        Authentication file                               
  --static, -s       Set static files directory
  --read-only, --ro  Allow only GET requests                           [boolean]
  --no-cors, --nc    Disable Cross-Origin Resource Sharing             [boolean]
  --no-gzip, --ng    Disable GZIP Content-Encoding                     [boolean]
  --snapshots, -S    Set snapshots directory                      [default: "."]
  --delay, -d        Add delay to responses (ms)
  --id, -i           Set database id property (e.g. _id)         [default: "id"]
  --foreignKeySuffix, --fks  Set foreign key suffix, (e.g. _id as in post_id)
                                                                 [default: "Id"]
  --quiet, -q        Suppress log messages from output                 [boolean]
  --help, -h         Show help                                         [boolean]
  --version, -v      Show version number                               [boolean]

  hai-server db.json
  hai-server file.js
  hai-server http://example.com/db.json


You can also set options in a hai-server.json configuration file.

  "port": 3000


If you need to add authentication, validation, or any behavior, you can use the project as a module in combination with other Express middlewares.

Simple example

$ npm install hai-server --save-dev
// server.js
const jsonServer = require('hai-server').haijsServer
const server = jsonServer.create()
const router = jsonServer.router('db.json')
const middlewares = jsonServer.defaults()

server.listen(3000, () => {
  console.log('HAI Server is running')
$ node server.js

The path you provide to the jsonServer.router function is relative to the directory from where you launch your node process. If you run the above code from another directory, it’s better to use an absolute path:

const path = require('path')
const router = jsonServer.router(path.join(__dirname, 'db.json'))

For an in-memory database, simply pass an object to jsonServer.router().

Please note also that jsonServer.router() can be used in existing Express projects.

Custom routes example

Let's say you want a route that echoes query parameters and another one that set a timestamp on every resource created.

const jsonServer = require('hai-server').haijsServer
const server = jsonServer.create()
const router = jsonServer.router('db.json')
const middlewares = jsonServer.defaults()

// Set default middlewares (logger, static, cors and no-cache)

// Add custom routes before HAI Server router
server.get('/echo', (req, res) => {

// To handle POST, PUT and PATCH you need to use a body-parser
// You can use the one used by HAI Server
server.use((req, res, next) => {
  if (req.method === 'POST') {
    req.body.createdAt = Date.now()
  // Continue to HAI Server router

// Use default router
server.listen(3000, () => {
  console.log('HAI Server is running')

Access control example

Create a file name auth.json similar like the one shown below. Provide your own secretKey, expiresIn, and collection of authenticated users. Here the authenticatedURL indicates the collection of URL's that needs authorization and authenticationURL is the URL to get accesstoken.

    "expiresIn": "1h",
    "users": [
          "id": 1,
          "name": "bruno",
          "email": "bruno@email.com",
          "password": "bruno"
          "id": 2,
          "name": "techie",
          "email": "techie@email.com",
          "password": "techie"
          "id": 3,
          "name": "nilson",
          "email": "nilson@email.com",
          "password": "nilson"

hai-server --watch db.json --auth auth.json --port 3000

How to login?

You can login by sending a POST request to

POST http://localhost:3000/auth/login

with the following data

  "email": "nilson@email.com",

You should receive an access token with the following format

   "access_token": "<ACCESS_TOKEN>"

You should send this authorization with any request to the protected endpoints

Authorization: Bearer <ACCESS_TOKEN>

Custom output example

To modify responses, overwrite router.render method:

// In this example, returned resources will be wrapped in a body property
router.render = (req, res) => {
    body: res.locals.data

You can set your own status code for the response:

// In this example we simulate a server side error response
router.render = (req, res) => {
    error: "error message here"

Rewriter example

To add rewrite rules, use jsonServer.rewriter():

// Add this before server.use(router)
  '/api/*': '/$1',
  '/blog/:resource/:id/show': '/:resource/:id'

Mounting HAI Server on another endpoint example

Alternatively, you can also mount the router on /api.

server.use('/api', router)



Returns an Express server.


Returns middlewares used by HAI Server.

  • options
    • static path to static files
    • logger enable logger middleware (default: true)
    • bodyParser enable body-parser middleware (default: true)
    • noCors disable CORS (default: false)
    • readOnly accept only GET requests (default: false)


Returns HAI Server router.





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