Got an API response or config file squashed onto a single unreadable line? This free json formatter spreads it back out with clean, consistent indentation, and flags the exact spot where the syntax breaks. Everything runs in your browser, so nothing is uploaded, no account is needed, and no signup stands between you and the result.
How to use this json formatter
Three quick steps — no signup, no cost.
Drop in a minified API response, a config snippet, or a whole document — messy spacing does not matter.
Choose 2 spaces, 4 spaces, or a tab, then format. Invalid input stops with an error message instead of silently mangled output.
Take the readable result back into your editor, your API client, or a config file.
Why a json formatter saves more time than reading raw output
Built for debugging, not just display.
When parsing fails you get the parser’s error message, so you can jump to the broken bracket instead of scanning hundreds of lines by eye.
Match your project’s style — 2 spaces, 4 spaces, or tabs — so formatted output pastes cleanly into existing files.
Nested objects and arrays get one level of indent each, which makes a missing brace or a wrongly nested array visible at a glance.
Parsing happens on your device, so API responses carrying tokens or customer data never travel to a server.
When formatting fails: the four mistakes behind nearly every error
Read this before you assume the tool is broken — the input usually is.
Trailing commas. Strict JSON has no place for a comma after the last item in an object or array, even though JavaScript allows one. Remove it and the document parses.
Single quotes. JSON strings and keys must use double quotes. Single-quoted text is JavaScript, not JSON, and every strict parser rejects it.
Unquoted keys and comments. Keys must be quoted strings, and JSON has no comment syntax at all. If your file came from a config format that allows comments, strip them first — or use a JSONC-aware editor instead.
The reported position is usually just past the real mistake. A message pointing at a closing brace often means a trailing comma sat one character earlier. Fix the character before the reported spot first.
One honest limit: very large integers can lose precision when parsed in JavaScript, because numbers become 64-bit floats. If an ID has more than about 15 digits, keep it as a quoted string.
JSON Formatter FAQs
Short, direct answers to the questions readers ask most.
It re-indents valid JSON with consistent line breaks and spacing so nested data is easy to read, and it reports syntax errors when the input is not valid JSON.
It stops and shows the parser’s error instead of guessing, because silently repairing a broken document could change its meaning.
No. Standard JSON has no comment syntax, so comments, single quotes, and trailing commas are all treated as errors.
Yes. Formatting only changes whitespace between tokens, never keys, values, or structure, so both versions parse to the same document.
Yes. It runs entirely in your browser with no account, no signup, and no upload.
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