JSON Formatter & Validator
Pretty-print, minify, and validate JSON instantly. Your data never leaves your browser.
How to use this tool
Paste JSON into the input box, then choose "Format" to pretty-print it, "Minify" to compact it onto one line, or "Validate only" to just check whether it's valid JSON without changing the output box.
About this tool
Formatting, minifying, and validation all use your browser's built-in, standards-compliant JSON parser (JSON.parse / JSON.stringify) — the same parser used by every major JavaScript engine — so results match what any JSON-consuming code would actually accept.
100% client-side. Nothing you paste is uploaded, logged, or stored.
Frequently asked questions
Is my JSON data uploaded anywhere?
No. All parsing, formatting, and validation happens locally in your browser using JavaScript's built-in JSON parser. Nothing you paste is ever sent to a server.
Why does it say my JSON is invalid?
Common causes: trailing commas (not allowed in JSON), single quotes instead of double quotes, unquoted object keys, comments (JSON has no comment syntax), or a missing/extra bracket or brace. The error message includes the position where parsing failed.
What's the difference between formatting and minifying?
Formatting (pretty-printing) adds indentation and line breaks to make JSON easy to read. Minifying removes all unnecessary whitespace to make the JSON as compact as possible, useful for reducing payload size before sending it somewhere.