JSON Formatter & Validator

JSON is the language of APIs, configuration files and logs, but machine-generated JSON usually arrives as one long unreadable line. This formatter pretty-prints it with clean indentation, tells you instantly whether it is valid and points to the line and column of any error. It can also minify JSON for production and sort keys alphabetically to make two objects easier to compare.

Common uses

• Read and debug REST and GraphQL API responses.
• Validate package.json, tsconfig, composer.json and other configuration files.
• Minify JSON payloads to reduce size before sending or storing them.
• Sort keys to compare two JSON documents with the Text Diff Checker.

Tips for best results

• Use 2-space indentation for web projects and 4 spaces for many Python and Java code bases.
• If you see “Unexpected token”, look just before the reported position – the real mistake is often a missing comma on the previous line.
• Large numbers above 2^53 lose precision in JavaScript; keep IDs as strings.
• Convert JSON to a spreadsheet with JSON to Excel or JSON to CSV.

JSON rules in one minute

JSON (RFC 8259) supports objects, arrays, strings, numbers, true, false and null. Keys and strings must use double quotes, there are no comments, and the last item in an object or array must not have a trailing comma. Text should be UTF-8. These rules make JSON easy for every language to parse, from JavaScript and Python to Go, Rust and Swift.

Minify or beautify?

Beautified JSON is for humans: code reviews, documentation and debugging. Minified JSON removes all optional whitespace and is typically 10–30% smaller, which helps with storage, caching and network transfers, although gzip or Brotli compression on web servers narrows the gap. Keep a formatted copy in version control and minify at build time.