JSON Formatter & Validator

Format, validate, minify — and when you'd want each

Pretty-printing (formatting) adds indentation and line breaks so a human can read or diff the structure — the move when an API hands you a single 4,000-character line. Minifying strips every optional space and newline for the opposite reason: the smallest payload to ship over the wire or embed in a config. Validation is the quiet one that matters most — it parses the text with the browser's native JSON.parse, per RFC 8259, and points at the exact position of the first syntax error, which is usually a trailing comma, a missing quote, or a stray newline inside a string.

The errors that trip people up

• Trailing commas — legal in a JavaScript object, illegal in JSON. {"a":1,} fails; this is the single most common paste error.
• Single quotes — JSON requires double quotes on both keys and string values, so 'key' is invalid.
• Comments — JSON has none. // and /* */ belong to JSON5/JSONC; strip them before parsing.
• Unquoted keys — {key:1} is a JS object literal, not JSON; it must be {"key":1}.
• Unescaped control characters — a literal newline or tab inside a string has to be written \n or \t.

Why 'sort keys' is more than tidiness

Sorting keys recursively produces canonical JSON: the same data always serialises to the same bytes no matter what order a program emitted the keys. That's what makes two config files diff cleanly in Git instead of showing phantom reorderings, and it's a prerequisite for any signature or hash over a JSON document — sign the canonical form or the signature breaks the moment a key order changes. If you're hashing canonical JSON, the SHA-256 hasher takes the sorted output directly.

Pasting real payloads safely

API responses and webhook bodies routinely carry tokens, session ids, email addresses and internal URLs. Because this formatter runs entirely in your tab — no request leaves the page — pasting a production payload to debug it is safe in a way that server-backed 'JSON beautifier' sites are not. Still, scrub anything you then copy into a bug report or screenshot. Spotted a JWT in the payload and want to read its claims, or need to turn a CSV export into JSON? Reach for CSV ↔ JSON.