JSON Formatter & Validator
Beautify, minify or validate JSON with a collapsible tree view, exact line/column error locations, adjustable indent width and key sorting.
These settings are kept in this browser only — what you paste is not kept, and nothing is uploaded.
Format and check JSON in one place
Paste JSON and click Beautify to pretty-print it with clean indentation, Minify to strip whitespace for the smallest size, or Validate to confirm it parses and see the exact error if it doesn't. Everything runs in your browser, so your data never leaves your device. To turn the JSON into another format, use JSON to CSV or JSON to XML.
Frequently asked questions
Is my JSON sent to a server?
No. Formatting and validation happen entirely in your browser using the built-in JSON parser. What you paste is not kept either: it is gone when you leave the page. Only the settings — indent, tab, key sorting, live formatting and the last mode — are remembered in this browser's local storage, and “Forget saved settings” erases them.
Why does it say my JSON is invalid?
The validator shows the parser error, which usually points to a trailing comma, a missing quote, or single quotes used instead of double quotes.
Why did large ID numbers change after formatting?
JavaScript stores every JSON number as a 64-bit float, so integers beyond 9,007,199,254,740,991 (Discord/Twitter Snowflake or database bigint IDs) get rounded. The tool warns when your JSON contains one — keep those IDs as quoted strings to preserve them exactly.
How do I find exactly where my JSON is broken?
When parsing fails, the tool reads the browser JSON error and reports the offending character as "line X, column Y" — jump to that spot in the Source pane instead of hunting through a giant blob.
Can I change the indentation or sort the keys?
Yes — set the indent to any whole number of spaces from 0 to 10, or tick "Use a tab", and tick "Sort keys" to alphabetize every object before beautifying.