JSON Formatter & Validator

JSON (JavaScript Object Notation) is a lightweight, text-based format for exchanging data. It is used everywhere, from REST APIs and configuration files to databases and logs. JSON is easy for machines to parse, but minified or poorly indented JSON is hard for people to read.

The DeveloperKit JSON Formatter turns messy JSON into clean, indented output and validates it at the same time. When something is wrong, you see exactly where and why, so you can fix it in seconds.

• Live validation

  Your JSON is checked as you type. Errors show the exact line and column, with a plain-English explanation and a jump-to-error button.

• Beautify and minify

  Pretty-print with 2, 3, or 4 spaces or tabs, or compress JSON into a single line to save bytes.

• Tree view

  Explore deeply nested objects and arrays in a collapsible tree to understand the structure at a glance.

• Files in, files out

  Upload or drag and drop a .json file, then copy the result or download it as a file.

• Private by design

  Everything runs locally in your browser. Your data is never sent to a server, logged, or stored.

• Built for large files

  Large inputs are processed efficiently so the editor stays responsive, even with thousands of lines.

1. Paste your JSON into the Input editor, or upload or drop a .json file.
2. The tool validates it instantly and shows any error with its line and column.
3. Choose Beautify or Minify, and pick your preferred indentation.
4. Switch to Tree view to explore the structure, if you like.
5. Copy the result to your clipboard or download it as a file.

A valid JSON document with objects, arrays, strings, numbers, booleans, and null:

{
  "id": 1042,
  "name": "DeveloperKit",
  "active": true,
  "tags": ["json", "formatter"],
  "owner": {
    "username": "devkit",
    "verified": false
  },
  "license": null
}