🧩 JSON Formatter
Beautify, validate, or minify JSON entirely in your browser — turn a tangled one-liner into readable, indented structure, or collapse a pretty file back down for transport.
🧹 Format, Validate & Minify
What is a JSON Formatter?
A JSON formatter re-indents JSON so its nesting is easy to read and review, and it doubles as a validator: if the text parses, it is valid. Minifying does the reverse, stripping whitespace for compact payloads.
It is a daily helper when you are debugging API responses, editing config files, or preparing data for a commit — readable when you work, compact when you ship.
❓ Frequently Asked Questions
Does this validate my JSON?
Yes. The formatter first parses your input with the browser's own JSON parser, so anything it can beautify or minify is valid JSON, and malformed input gets the parser's error message instead of a broken result. It then re-spaces your original text rather than re-printing the parsed values, so nothing in the data changes.
Why would a formatter change my numbers?
Many formatters parse the JSON into JavaScript values and print them again, which quietly rewrites data: 12345678901234567890 comes back as 12345678901234567000, 1e400 comes back as null, and the first of two duplicate keys disappears. This one keeps every number and string exactly as written and warns you instead, because the program that reads your JSON will hit the same limits. RFC 8259 says integers in the range [-(2**53)+1, (2**53)-1] are interoperable, so send longer IDs as strings, and that when names in an object are not unique, the behavior of receiving software is unpredictable.
What is the difference between formatting and minifying?
Formatting (beautifying) adds consistent indentation and line breaks so a human can read and diff the structure easily. Minifying strips every optional space and newline to produce the smallest single-line form, which is what you want for payloads sent over the network or embedded in code.
Is my JSON uploaded anywhere?
No. Parsing, pretty-printing, and minifying all happen locally in your browser. Your data never leaves the page, so it is safe to paste API responses, config files, or other snippets you would rather not send to a server. If you open the kit offer below, it carries only the minified size and the number of warnings, never your JSON.
Why am I getting an 'Unexpected token' error?
That error means the text is not valid JSON. Common causes are trailing commas, single quotes instead of double quotes, unquoted keys, comments (JSON does not allow them), or a stray character copied from a log. Fix the highlighted spot and re-run to get clean output.