JSON Formatter
This online JSON formatter reads any JSON you paste, checks its syntax, and returns it pretty-printed or minified — all locally, without sending your data to a server.
Format, validate and minify JSON instantly in your browser.
Paste JSON of any shape — it stays on your device.
Valid JSON, 0 lines
How to use JSON Formatter
- Paste your JSON into the input box (or type it directly).
- Use the segmented control to pretty-print, minify, or validate.
- Fix any syntax error the validator highlights and format again.
- Use the copy button to take the result to your editor or API client.
Frequently asked questions
Does my JSON get uploaded to a server?
No. Formatting and validation happen entirely in your browser — the data never leaves your device.
How large can a JSON file be?
Comfortably up to a few megabytes. Very large files are limited by your browser's memory rather than any upload size, because nothing is uploaded.
Can it tell me where the syntax error is?
Yes. The validator points to the first offending character, including its position in the input, so you can correct spreadsheets, API responses, and config files quickly.
Does it support minified and pretty output?
Yes. Switch between Pretty and Minify to either expand JSON with indentation or strip all unnecessary whitespace.