Input
Size: 0 B Lines: 0
Output 
Formatted output will appear here...
Size: 0 B Lines: 0
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All processing is done in your browser. Nothing is uploaded or stored. Ctrl+Enter to format

JSON Formatter & Validator — Free Online Tool

How to use

  1. Paste or type raw JSON into the Input panel
  2. Click Format to pretty-print with syntax highlighting
  3. Click Minify to compress into a single line
  4. Use the indent selector to switch between 2 spaces, 4 spaces, or tabs
  5. Click Copy to copy the output to your clipboard
  6. Errors display the exact line number and a hint to fix it

Features

  • Pretty-print JSON with configurable indentation
  • Minify JSON to a single line for production use
  • Instant validation with descriptive error messages
  • Syntax highlighting for keys, strings, numbers, and booleans
  • Paste from clipboard in one click
  • 100% client-side — nothing is sent to a server
  • Works offline once the page is loaded

Frequently asked questions

Is my JSON data sent to a server?
No. All processing happens entirely in your browser using JavaScript. Your data never leaves your device.
What is JSON formatting?
JSON formatting (also called pretty-printing or beautifying) adds indentation and line breaks to compact JSON to make it human-readable. Minifying does the reverse — it strips all whitespace to reduce file size.
What's the maximum file size this tool can handle?
There is no hard server-side limit since processing is local. Very large files (10MB+) may slow down depending on your device's browser and available memory.
Does it support JSON5 or JSONL?
This tool validates strict RFC 8259 JSON. JSON5 (with comments, trailing commas) and JSONL (line-delimited JSON) are not supported in this version.