Summary

This free JSON formatter validates, formats, and minifies JSON directly in your browser. Paste raw data and it runs the string through JSON.parse, reports the exact line and column of any syntax error, and lets you switch between 2-space, 4-space, or tab indentation, or strip it down with minify to cut payload size. Nothing you paste leaves your browser: the entire calculation runs client-side, with no signup and no file upload.

Format, Validate, and Minify JSON in Your Browser

This free json formatter parses your data locally, flags the exact line where it breaks, and outputs clean, indented, or minified JSON with zero server round trip. Built for the moment you paste an API response into your editor and it's one long unreadable line, or the moment a build fails because of a trailing comma nobody can see.

Try it now

JSON formatter

Paste raw JSON on the left. It validates and formats as you type, no button required.

Formatted output
Paste JSON above. It formats as you type.
Under the hood

How this JSON formatter works

Real JSON.parse, not a regex guess

The validator runs your input through the JavaScript engine's own JSON.parse. If a comma is trailing, a key is unquoted, or a control character slipped in from a copy-paste, it throws the same error your browser console would throw. No approximation, no separate parser with its own quirks.

Line and column, not just 'invalid'

A parse failure returns a character position, which is close to useless on a 4 000-character blob. This tool converts that position into a line and column number, so you scroll straight to the broken brace instead of scanning the whole payload by eye.

2 spaces, 4 spaces, or a tab

Pick the indent your linter expects, or hit Minify to strip every space before you paste the payload into a request body or a config file. The output updates live as you type, and the byte count below it tells you exactly how much you saved.

Before and after

One paste, two views

Drop in a minified API response, a log line, or a hand-typed object. The tool does not care about existing whitespace, trailing newlines, or whether the source was a curl response or a config file you're about to hand-edit. What comes back is color-coded: keys, strings, numbers, booleans, and null values, indented exactly the way you asked.

  • Raw input: paste anything, whitespace and all
  • Formatted output: color-coded, indented, copy-ready in one click
  • Stats line: key count and byte difference at a glance
Backlit mechanical keyboard next to a stopwatch, representing fast client-side JSON formatting
Workflow

Paste, read, copy

  1. 1

    Paste your JSON

    Drop the raw text into the left panel. There is no upload button and no file picker, because the string never leaves the tab.

  2. 2

    Read the result

    A green status line means the structure parsed cleanly. A red one names the exact line and column where it broke, so you fix the source instead of guessing.

  3. 3

    Copy or switch modes

    Hit Format for a readable, indented version, or Minify for the smallest byte count. Copy output puts the current view straight on your clipboard.

Common questions

Is this JSON formatter free?
Yes. No signup, no rate limit, no watermark added to the output.
Does my JSON get sent to a server?
No. Parsing, formatting, and minifying all run in your browser's own JavaScript engine. Nothing you paste is transmitted anywhere.
What's the difference between formatting and minifying?
Formatting adds indentation and line breaks so a human can read the structure. Minifying strips every space and newline so the same data ships in fewer bytes over the wire.
Why does the error say 'Unexpected token' instead of 'invalid JSON'?
That's the exact message JSON.parse throws. This tool also converts the character position it reports into a line and column, so you can find the broken brace fast.
Does it support comments or trailing commas (JSONC/JSON5)?
No. It validates strict JSON per RFC 8259. Comments and trailing commas are the two most common causes of the 'Unexpected token' error you'll see here.
Is there a size limit on what I can paste?
No hard limit is enforced, but very large payloads, multiple megabytes, will feel slower, since the whole string is parsed in memory in your browser tab.
Can I get 4-space indentation or tabs instead of 2 spaces?
Yes. The indent selector switches between 2 spaces, 4 spaces, and a tab character, and the output re-renders immediately.

One tool. One job. See what else we ship.

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