Format, validate and minify JSON
Built & maintained by Pappu Venkata Subbi Reddy, founder of Clacify
The JSON Formatter beautifies, validates, and minifies JSON data directly in your browser. Paste messy or minified JSON and it pretty-prints it with proper indentation and syntax highlighting; if there is a syntax error, it points to where the problem is so you can fix it fast. A minify mode strips all whitespace to produce the smallest valid output for APIs and config files. Developers use it dozens of times a day to inspect API responses, clean up log output, and debug payloads. Because it runs entirely client-side, you can safely format JSON containing tokens, keys, or customer data without it ever being sent to a server.
The tool parses your input with the browser's native JSON engine (JSON.parse), which both validates the structure and surfaces precise error messages — including the position — when the JSON is malformed. Valid data is re-serialised with JSON.stringify using a configurable indentation (typically two spaces) for the beautify view, or with no whitespace for the minify view. Syntax highlighting is applied to the formatted output for readability. All parsing and formatting happen locally in JavaScript; your data never touches a network, so it is safe for payloads containing credentials or personal information.
JSON looks like a JavaScript object but is stricter, and almost every "invalid JSON" error traces back to one of a small set of rules. Keys must always be wrapped in double quotes — {name: "Raj"} is valid JavaScript but invalid JSON; it must be {"name": "Raj"}. Single quotes are never allowed anywhere, for keys or string values. Trailing commas — a comma after the last item in an array or object, e.g. [1, 2, 3,] — are permitted in JavaScript but rejected by strict JSON parsers, including the one this tool uses, which is exactly why it matches what your backend or API will actually accept.
Numbers cannot have leading zeros (01 is invalid, 1 is valid), cannot be NaN or Infinity, and cannot include trailing decimal points. Comments are not part of the JSON specification at all — not even the // or /* */ styles from JavaScript or C — so any JSON containing comments (common in hand-edited config files) will fail to parse until they are stripped. When this tool reports an error, it is reporting exactly where JSON.parse — the same engine every browser and most backend JSON libraries use — stopped being able to make sense of the input, so fixing that one spot is usually enough to make the whole document valid.
Beautified (pretty-printed) JSON, with indentation and line breaks, is for humans — reviewing an API response, debugging a payload, or reading a config file. Minified JSON, with all whitespace removed, is for machines: it is smaller to transmit over a network and marginally faster to parse, which is why production APIs typically send minified JSON and why minifying your own config files or request bodies before shipping them can shave real bytes off every request. The two representations are semantically identical — the same data, the same keys, the same values — so converting between them never changes what the JSON actually means, only how many bytes it takes and how easy it is for a person to read.
JSON won out over XML for most web APIs because it maps directly onto the data structures every mainstream programming language already has — objects, arrays, strings, numbers, booleans, and null — with none of XML's attribute-vs-element ambiguity or closing-tag overhead. YAML is a superset-ish alternative popular for config files (Docker Compose, Kubernetes, CI pipelines) because it drops the braces and quotes for something more human-typable, but that same flexibility makes it more error-prone for machine-to-machine communication, which is why JSON remains the standard for REST APIs, webhooks, and anywhere two systems — not two humans — are exchanging data.
Paste your JSON into Clacify's JSON Formatter and it instantly indents and syntax-highlights it. If the JSON has errors, the validator highlights the exact location. Click Minify to compress it back into a single line for production use.
Beautifying adds indentation and newlines to make JSON readable for humans. Minifying removes all whitespace to produce the smallest possible string — ideal for API responses and config files to reduce data transfer size and improve load times.