JSON Formatter and Validator
Beautify, minify and validate JSON instantly — with clear error messages when something is off.
What is it?
A JSON formatter is a tool that takes raw JSON text, parses it and reprints it with consistent indentation, sorted or preserved keys and clear spacing. Our free online JSON formatter does all of that, plus it validates the input: if the JSON is malformed, you get a precise error message with line and column pointing to the issue. You can also minify the same JSON for use inside a config, a URL or a mobile payload where size matters. Everything runs in your browser, so even private API responses can be formatted safely — nothing is transmitted to a server.
How to use it
- Paste your JSON string into the input area.
- Click “Format” to get a nicely indented version, or “Minify” to strip all whitespace.
- If the JSON is invalid, the error panel shows the exact line and reason.
- Adjust the indentation (2 or 4 spaces) or switch between compact and expanded output.
- Use “Copy” to copy the result, or “Download” to save it as a .json file.
Why use this tool
JSON is the lingua franca of modern web APIs, configuration files and data pipelines, but it is famously strict: one missing comma, one unescaped quote, and the whole payload is unusable. A good formatter does more than just indent — it parses the document, flags errors in plain language and reformats the output in a consistent, diff-friendly way. Developers use a JSON formatter every day when inspecting API responses, preparing fixtures for tests, sharing data with a teammate or cleaning up an export. Minifying back to a single line is equally important when sending JSON inside URLs, localStorage or mobile apps where every byte counts. Because the whole process happens locally, you can format responses that contain access tokens, personal data or internal identifiers without worrying about leaks.
Frequently asked questions
Does the formatter support JSON with comments?
Strict JSON does not allow comments, so the formatter rejects them. A “lenient” mode can be added on request for JSON5 or JSONC.
What does “minify” do exactly?
Minifying removes every unnecessary whitespace and newline so the JSON fits on a single line, making the payload as small as possible without changing its meaning.
Is my JSON uploaded anywhere?
No. Parsing and formatting happen entirely in your browser. No data ever leaves your device.
Why do I get an “Unexpected token” error?
That error means the parser found a character it did not expect — usually a missing comma, an extra comma or an unquoted key. The error panel shows the exact position.
Can it sort keys alphabetically?
Yes. Turn on the “Sort keys” option and objects at every depth will be reformatted with alphabetically ordered keys for easier diffing.