JSON Formatter & Validator
Beautify, minify and validate JSON — syntax errors are pinpointed to the exact line.
Free · No sign-up · Runs locally in your browser · Also available in Chinese (中文)
What is JSON Formatter & Validator?
A JSON formatter takes raw, minified or messy JSON and reprints it with consistent indentation, sorted keys and aligned brackets, so humans can actually read it. The same run doubles as a strict validator: if the input is not well-formed JSON, the tool reports the error with its line and column position instead of a vague generic message.
JSON (JavaScript Object Notation) is the de-facto interchange format for APIs, config files and log pipelines. Because every language that talks over HTTP now handles JSON, formatting and validating it is a daily task for developers, QA engineers and data analysts. This tool does all of it locally in your browser — your API responses, tokens and config files never leave your device.
How to use it
- 1Paste your JSON into the input box, or drag a .json file onto the page.
- 2Click Format to beautify with 2-space indentation, or Minify to strip all whitespace.
- 3If the JSON is invalid, read the error message — it names the line and column to fix.
- 4Copy the result to the clipboard or download it as a .json file.
Common use cases
- Debugging an API response that arrived minified in a single 20,000-character line.
- Validating a JSON config file (package.json, tsconfig, CI settings) before committing it.
- Comparing and re-indenting JSON exported from a database or spreadsheet.
Frequently asked questions
▸Does formatting change my data?
No. Formatting only changes whitespace and indentation. Keys, values and their order are preserved exactly as they were.
▸Is there a size limit?
The tool runs entirely in your browser, so the practical limit is your device's memory. Files of several megabytes format in well under a second on a normal machine.