JSON Formatter & Validator
Format, minify and validate JSON instantly — with exact error positions when something's wrong.
About this tool
A malformed JSON payload can stall an entire debugging session — one missing comma buried in a wall of unformatted text. This formatter turns compressed, single-line JSON into cleanly indented, readable structure in one click, and validates it at the same time using the browser's native JSON engine — the exact same parser that runs your production JavaScript. If your JSON is invalid, you get the engine's own error message with the character position, so you know precisely where to look.
Choose 2-space or 4-space indentation to match your team's style guide, or go the other way: minify formatted JSON into a compact single line for API payloads, config files and reduced transfer sizes.
Because everything runs locally in your browser, this tool is safe for the JSON developers actually work with — API responses containing user data, auth tokens, internal config. Nothing is uploaded, logged or stored. Paste a response from Postman, an API log, or a config file, and it never leaves your machine. That's a guarantee most online formatters can't make.
How to use the JSON Formatter & Validator
- 1Paste your JSON into the input box (or click Load sample to try it).
- 2Click Format for readable, indented output — choose 2 or 4 spaces.
- 3Click Minify instead to compress it to a single line.
- 4If the JSON is invalid, read the error message — it includes the exact position of the problem.
- 5Click Copy result to grab the output.
Frequently asked questions
Is my JSON sent to a server?
No. Formatting, minifying and validation all run in your browser using JavaScript's built-in JSON engine. Your data — including API responses with sensitive content — never leaves your device.
What's the difference between formatting and minifying?
Formatting (also called beautifying or pretty-printing) adds indentation and line breaks so humans can read the structure. Minifying removes all unnecessary whitespace to produce the smallest possible output for machines — ideal for API payloads and production configs.
Why does it say my JSON is invalid?
Common causes: trailing commas after the last item, single quotes instead of double quotes, unquoted property names, or comments (standard JSON doesn't allow them). The error message shows the position where parsing failed — the actual mistake is usually at or just before that spot.
Can it handle large JSON files?
Yes. Because parsing happens locally with the browser's native engine, files of several megabytes format almost instantly — no upload time, no server limits.
Does it change my data in any way?
No. Formatting only changes whitespace. Keys, values, ordering and structure are preserved exactly — the formatted and minified versions are semantically identical to your input.
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