JSON-Server

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Install

npm install json-server

Usage

Create a db.json or db.json5 file

{
  "$schema": "./node_modules/json-server/schema.json",
  "posts": [
    { "id": "1", "title": "a title", "views": 100 },
    { "id": "2", "title": "another title", "views": 200 }
  ],
  "comments": [
    { "id": "1", "text": "a comment about post 1", "postId": "1" },
    { "id": "2", "text": "another comment about post 1", "postId": "1" }
  ],
  "profile": {
    "name": "typicode"
  }
}

{
  posts: [
    { id: "1", title: "a title", views: 100 },
    { id: "2", title: "another title", views: 200 },
  ],
  comments: [
    { id: "1", text: "a comment about post 1", postId: "1" },
    { id: "2", text: "another comment about post 1", postId: "1" },
  ],
  profile: {
    name: "typicode",
  },
}

Start JSON Server

npx json-server db.json

This starts the server at http://localhost:3000. You should see:

JSON Server started on PORT :3000
http://localhost:3000

Access your REST API:

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

Response:

{
  "id": "1",
  "title": "a title",
  "views": 100
}

Run json-server --help for a list of options

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Query Capabilities

JSON Server supports advanced querying out of the box:

GET /posts?views:gt=100                  # Filter by condition
GET /posts?_sort=-views                  # Sort by field (descending)
GET /posts?_page=1&_per_page=10          # Pagination
GET /posts?_embed=comments               # Include relations
GET /posts?_where={"or":[...]}           # Complex queries

See detailed documentation below for each feature.

Routes

Array Resources

For array resources like posts and comments:

GET    /posts
GET    /posts/:id
POST   /posts
PUT    /posts/:id
PATCH  /posts/:id
DELETE /posts/:id

Object Resources

For singular object resources like profile:

GET   /profile
PUT   /profile
PATCH /profile

Query params

Conditions

Use field:operator=value.

Operators:

• no operator -> eq (equal)
• lt less than, lte less than or equal
• gt greater than, gte greater than or equal
• eq equal, ne not equal
• in included in comma-separated list
• contains string contains (case-insensitive)
• startsWith string starts with (case-insensitive)
• endsWith string ends with (case-insensitive)

Examples:

GET /posts?views:gt=100
GET /posts?title:eq=Hello
GET /posts?id:in=1,2,3
GET /posts?author.name:eq=typicode
GET /posts?title:contains=hello
GET /posts?title:startsWith=Hello
GET /posts?title:endsWith=world

Sort

GET /posts?_sort=title
GET /posts?_sort=-views
GET /posts?_sort=author.name,-views

Pagination

GET /posts?_page=1&_per_page=25

Response:

{
  "first": 1,
  "prev": null,
  "next": 2,
  "last": 4,
  "pages": 4,
  "items": 100,
  "data": [
    { "id": "1", "title": "...", "views": 100 },
    { "id": "2", "title": "...", "views": 200 }
  ]
}

Notes:

• _per_page defaults to 10 if not specified
• Invalid _page or _per_page values are automatically normalized to valid ranges

Embed

GET /posts?_embed=comments
GET /comments?_embed=post

Complex filter with _where

_where accepts a JSON object and overrides normal query params when valid.

GET /posts?_where={"or":[{"views":{"gt":100}},{"author":{"name":{"lt":"m"}}}]}

Delete dependents

DELETE /posts/1?_dependent=comments

Static Files

JSON Server automatically serves files from the ./public directory.

To serve additional static directories:

json-server db.json -s ./static
json-server db.json -s ./static -s ./node_modules

Static files are served with standard MIME types and can include HTML, CSS, JavaScript, images, and other assets.

Migration Notes (v0 → v1)

If you are upgrading from json-server v0.x, note these behavioral changes:

• ID handling: id is always a string and will be auto-generated if not provided
• Pagination: Use _per_page with _page instead of the deprecated _limit parameter
• Relationships: Use _embed instead of _expand for including related resources
• Request delays: Use browser DevTools (Network tab > throttling) instead of the removed --delay CLI option

New to json-server? These notes are for users migrating from v0. If this is your first time using json-server, you can ignore this section.