How it works

How the JSON Formatter & Validator works

Format, minify and validate JSON with error messages that tell you the line and column. Runs locally — safe for payloads you should not paste into a website.

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The method

Parsing uses the native JSON.parse, the fastest and most standards-accurate option available. Its errors only give a character offset, so we convert that into a line and column and show the offending line — turning "unexpected token at position 1043" into "trailing comma on line 42."

Step by step

1
Paste your JSON.
2
Choose an indent width, or minify.
3
Read the error location if it fails to parse.
4
Copy the result.

What it doesn't do

Strict JSON only — comments, trailing commas and single-quoted strings are reported as errors, not silently fixed.
Integers beyond 2^53 lose precision; JavaScript numbers are IEEE-754 doubles.

Frequently asked

Is my JSON sent to a server?

No, and that is the point of this one. Everything runs in your tab, so it is safe for API responses and payloads you should not be pasting into arbitrary websites.

Why is my JSON invalid when it looks fine?

The usual culprits are a trailing comma before a closing brace, unquoted keys, or single quotes instead of double quotes. All three are valid JavaScript and invalid JSON.

What indent should I use?

Two spaces is the most common convention. Minify for anything going over the wire.

Need this built into your business?

This tool is free because it's a small, solved problem. If what you actually need is bigger — what Scult builds, built and maintained for you — that's Scult's day job.

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