JSON Formatter
Beautify, minify or validate JSON.
Results appear as you type
Everything runs locally in your browser — your input never leaves this page.
About the JSON Formatter
The JSON Formatter beautifies messy JSON with clean indentation, minifies it to the smallest possible size, and validates it while pinpointing syntax errors. It makes deeply nested API responses readable and helps you catch a stray comma or missing bracket before it breaks your code. All parsing happens in your browser, so sensitive payloads never leave your machine.
How to use
- Paste your JSON into the input area.
- Choose beautify, minify or validate.
- Read the formatted output or the location of any syntax error.
- Copy the cleaned-up JSON for use in your project.
What a JSON validator can and cannot tell you
A parser answers one question: is this document syntactically valid JSON? That is narrower than it sounds. The format has no comments, no trailing commas, and requires double quotes on both keys and string values — three things people write by habit from JavaScript and then spend ten minutes hunting. If a paste fails and looks fine, check for a trailing comma before the closing brace first; it is by far the most common cause.
Valid does not mean correct. `{"port": "8080"}` and `{"port": 8080}` are both valid documents, and exactly one of them will work with a consumer expecting a number. The same applies to `null` versus a missing key: a parser accepts both, while the code reading it often treats them very differently. Schema validation is a separate step, and no formatter performs it.
Two details bite in practice. Numbers have no defined precision in the spec, so a 64-bit integer such as a Twitter-style ID or a database primary key can lose accuracy when parsed into a JavaScript double — which is why APIs that care serialise large IDs as strings. And duplicate keys are not an error: the specification leaves the behaviour undefined, most parsers keep the last occurrence, and the first is silently discarded.
Frequently asked questions
- What is the difference between beautifying and minifying?
- Beautifying adds indentation and line breaks to make JSON human-readable, while minifying strips all unnecessary whitespace to reduce size for transmission or storage. Both produce equivalent data.
- Why does my JSON fail validation?
- Common causes are trailing commas, single quotes instead of double quotes, unquoted keys, or comments, none of which are allowed in strict JSON. The validator reports where parsing failed.
- Is it safe to paste private API data here?
- Yes. The formatter runs completely client-side in your browser, so your JSON is never uploaded to any server.