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JSON Formatter & Validator

Format, validate, and minify JSON instantly — syntax highlighting, auto-format on paste, and one-click download. Runs entirely in your browser.

This tool formats, validates and minifies JSON in your browser. Paste raw JSON to get an indented, readable version with syntax errors reported by line and position, or minify it to strip whitespace for transport. Nothing is sent to a server, so it is safe to use on payloads containing real data.

Paste or type JSON — it validates as you type
Indent:

Input

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Outputread-only

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About this tool

A fast, privacy-first JSON formatter that works offline. Paste raw JSON from an API response, config file, or log — it validates immediately and auto-formats on paste. Use Format to pretty-print with 2 or 4-space indentation, or Minify to strip all whitespace. Download the result as a .json file or copy it to the clipboard.

The editor uses Monaco (the engine behind VS Code) for syntax highlighting, line numbers, and bracket matching. Your data never leaves your device.

How to use

1

Paste your JSON

Paste raw JSON into the editor. It validates immediately and auto-formats on paste if the input is valid.

2

Format or Minify

Click Format to pretty-print with indentation, or Minify to strip all whitespace for the smallest possible output.

3

Adjust indent size

Use the indent toggle in the toolbar to switch between 2-space and 4-space indentation before formatting.

4

Copy or Download

Click Copy to copy the result to clipboard, or Download to save it as a .json file.

At a glance

Operations
Format with indentation, validate, and minify
Error reporting
Syntax errors are reported with line and position, not just a generic failure
Parser
The browser's own JSON parser, so behaviour matches what your code will see
Minify
Strips whitespace for transport; the parsed value is identical
Safe for real data
Nothing is sent to a server, so payloads containing production values can be pasted here

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Frequently asked questions

Common questions about the JSON formatter and validator.

Last updated

No. All formatting, validation, and minification happen entirely in your browser. Nothing is sent to a server.

Format pretty-prints JSON with indentation and line breaks for readability. Minify strips all whitespace to produce the smallest possible output — useful for APIs and storage.

Common causes include trailing commas, single-quoted strings, unquoted keys, or comments. JSON requires double quotes for strings and keys, no trailing commas, and no comments.

Yes — use the Indent toggle in the toolbar to switch between 2-space and 4-space indentation before clicking Format.

Yes. When you paste valid JSON into the input editor it is automatically formatted using the current indent setting.