What it does
Make JSON readable, check that it’s valid, or shrink it for production. Errors point to the exact line and column with a plain explanation, such as a trailing comma, a missing quote or a comment, which JSON doesn’t allow. Unlike many formatters, this one never changes your data: long numbers such as IDs keep every digit, and text keeps its escapes exactly as written. It also warns about duplicate keys, which most programs silently drop. Your JSON stays in your browser, so API responses and config files with secrets aren’t sent anywhere.
How to use it
- Paste your JSON into the box, drop a .json file onto it, or click “Open a file”.
- It’s checked as you type. If something is wrong, you’ll see the line, the column and what to fix; “Show me” puts the cursor right on it.
- Choose “Format” for readable, indented JSON or “Minify” for the smallest version, and optionally sort the keys.
- Copy the result, or download it as a .json file.
Common uses
- Reading a minified API response while debugging
- Finding the typo that breaks a config file such as package.json or tsconfig.json
- Minifying JSON before embedding it in a page or sending it over the network
- Sorting keys so two JSON files can be compared line by line in a diff
Tips
- JSON is stricter than JavaScript: keys and strings need double quotes, and trailing commas, comments, undefined and NaN aren’t allowed.
- IDs longer than 15–16 digits lose precision in JavaScript. If an ID looks different after JSON.parse, send it as a string instead.
- Duplicate keys are technically allowed, but different programs keep different values, so it’s safest to remove them.