JSON Formatter & Validator
Format, validate, and minify JSON — with clear error messages when something's wrong. Runs entirely in your browser.
JSON (JavaScript Object Notation) is a text-based format used to structure and exchange data between systems — it's the backbone of most modern web APIs, configuration files, and data exports. Because JSON follows strict syntax rules, a single missing comma, unmatched bracket, or misplaced quotation mark will make it invalid and unusable by the programs that need to read it. This tool checks your JSON against those rules and helps you clean it up, using your browser's built-in JSON engine so nothing you paste is sent to any server.
Paste your JSON into the input box and click "Format" to have it parsed and re-printed with consistent indentation, making nested objects and arrays much easier to read and review. You can choose between 2-space and 4-space indentation depending on your preference or your team's style guide. If you instead need a compact version — for example, to reduce the size of a JSON payload before sending it over a network or embedding it in a URL — click "Minify" to strip out all unnecessary whitespace and line breaks while keeping the data structure identical.
If the JSON you paste contains a syntax error, the tool will display a clear error message rather than silently failing or producing incorrect output. This typically includes details about what the parser expected versus what it found, which helps you quickly locate and fix issues like trailing commas, missing quotation marks around property names, or unclosed brackets — common mistakes when JSON is written or edited by hand.
Developers, API testers, and anyone working with configuration files or data exports use tools like this to debug malformed JSON responses, tidy up minified data for readability, prepare clean JSON for documentation or debugging logs, or double-check that hand-written JSON is valid before using it in code. Because formatting and validation both happen locally, it's safe to use even with JSON containing internal API keys, tokens, or other data you wouldn't want sent to an external service.
What happens if my JSON is invalid?+
You'll see an error message describing what's wrong, usually including the position where the parser got stuck, so you can find and fix the issue.
Is my JSON data uploaded anywhere?+
No. All formatting and validation happens locally in your browser — nothing is sent to a server.
Can I change the indentation?+
Yes, use the indent size selector to choose 2 or 4 spaces before formatting.
What's the difference between Format and Minify?+
Format adds line breaks and indentation to make the JSON easy to read. Minify removes all unnecessary whitespace to produce the smallest possible output.