JSON Formatter — Free Online Tool

Format, validate & minify JSON with error locations. · No signup · Works on mobile

Loading tool…

100% private: your data is processed in your browser. Nothing is uploaded to our servers.

How to use the json formatter

  1. 1

    Paste your JSON into the editor (or drop a .json file).

  2. 2

    Click Format to beautify, Minify to compress, or Validate to check syntax.

  3. 3

    Copy the output or download it as a .json file.

What does this tool do?

This free JSON formatter beautifies, validates, and minifies JSON instantly in your browser. Paste raw JSON to pretty-print it with your chosen indentation, get exact line-and-column error locations when it's invalid, or minify it for production — with nothing sent to any server.

How does the json formatter work?

Parsing uses the browser's native JSON.parse — the same strict RFC 8259 implementation used in production systems — so validation matches real-world behavior exactly. Formatting re-serializes with JSON.stringify at 2 or 4 spaces or tabs; errors are mapped back to line and column.

Frequently Asked Questions

What are the most common JSON syntax errors?

The top five: trailing commas after the last item (valid in JavaScript, illegal in JSON), single quotes instead of double quotes, unquoted keys, missing commas between items, and comments (JSON has no comment syntax). This validator points to the exact line and column of the first error.

Is JSON with comments (JSONC) valid?

Not in standard JSON — RFC 8259 has no comment syntax. JSONC (used by VS Code settings) and JSON5 are supersets that allow comments and trailing commas, but APIs and JSON.parse will reject them. Strip comments before sending data to any standard JSON consumer.

Is the JSON formatter really free?

Yes — 100% free with no hidden charges, trial limits, or premium tiers for core features. No account or email needed. The site is supported by non-intrusive display ads, which keeps every tool free for everyone.

Are my files private when using the JSON formatter?

Completely. The JSON formatter processes everything locally in your browser — your files are never uploaded to any server. When you close the tab, everything is gone. This makes it safe for confidential documents, client work, and personal photos.

Does the JSON formatter work on mobile phones?

Yes. It's built mobile-first and works on any modern phone browser — iPhone (Safari) and Android (Chrome) included. You can pick files straight from your camera roll and download results directly to your device.

Do I need to install any software to use the JSON formatter?

No. The JSON formatter runs entirely in your web browser — no downloads, extensions, or signup. Open the page, use the tool, download your result. It works on Windows, macOS, Linux, ChromeOS, iOS, and Android.