JSON Formatter
Format, validate, explore and minify JSON instantly — entirely in your browser.
About this tool
A JSON formatter takes raw, minified or messy JSON and rewrites it with consistent indentation and line breaks so you can actually read it. This one also works as a validator: if the syntax is broken, you get the exact parser error instead of a vague "invalid JSON" message.
Everything runs inside your browser using the native JSON parser. Nothing is uploaded, which matters because JSON payloads routinely contain API keys, access tokens, customer records and internal IDs — data you should not paste into a random server.
Because there is no upload step, there is also no file size limit and no waiting. Paste a 10 MB API response and it formats as fast as your device can parse it.
How to format JSON
- 1Paste JSON into the input box or open a local .json file — minified, pretty-printed or copied straight from a network tab.
- 2Choose an indentation width: 2 spaces (the most common convention), 4 spaces, or 8 for tab-like output.
- 3Click Format to beautify, Minify to strip all whitespace, or Validate to check syntax only.
- 4Read the result as formatted text or switch to the collapsible Tree view, then copy the output when needed.
What this tool does
Beautify and minify
Pretty-print JSON for reading and debugging, or minify it to a single line to reduce payload size in API responses and config files.
Precise error messages
Invalid JSON returns the browser's native parser error, which tells you the position of the problem — usually a trailing comma, single quotes or an unescaped character.
Unicode and escapes preserved
Non-Latin text, emoji and escaped sequences survive formatting untouched, because the tool re-serializes the parsed structure rather than editing text.
No size limit, no upload
Large payloads are handled locally by your device. Your JSON never reaches a server, so credentials inside it stay private.
Frequently asked questions
What does a JSON formatter actually do?
It parses your JSON into a data structure, then writes it back out with consistent indentation and line breaks. The data is identical — only the whitespace changes. This makes nested objects and arrays readable at a glance.
How do I validate JSON?
Paste it and click Validate. If the syntax is correct you get a confirmation; if not, you get the parser error describing what went wrong and roughly where. Formatting also validates implicitly, since invalid JSON cannot be parsed.
Why does my JSON say 'Unexpected token'?
The three most common causes are a trailing comma after the last item, single quotes instead of double quotes around keys or strings, and unescaped characters such as a raw newline inside a string. JSON is stricter than JavaScript object literals.
What is JSON minification for?
Minifying removes every unnecessary space and newline, producing the smallest valid representation. It is useful for API responses, embedded configuration and anywhere bytes on the wire matter. The parsed result is exactly the same.
Which indentation should I choose?
Two spaces is the dominant convention in JavaScript, TypeScript and most JSON style guides. Four spaces is common in Python and Java ecosystems. Pick whatever matches the file you are pasting into.
Is my JSON data sent to a server?
No. Formatting, minifying and validating all happen locally in your browser through the built-in JSON parser. Nothing is transmitted, logged or stored — you can verify this by opening your browser's network tab while using the tool, or by disconnecting from the internet after the page loads.
Is there a maximum file size?
There is no artificial limit. The practical ceiling is your device's available memory, which typically means multi-megabyte payloads format without trouble.
Does it support comments or trailing commas (JSON5)?
No. This tool follows the strict JSON specification, which does not allow comments or trailing commas. If your file contains them, it is JSON5 or JSONC and must be cleaned up first.