JSON Formatter
Beautify, minify and validate JSON in one click. Paste your JSON, get clean readable output with exact error locations when something is wrong. Everything runs in your browser; no signup, nothing is uploaded.
By UpnixTools · Tool last reviewed November 2026
Input JSON
Size: 0 BLines: 0
Formatted Output
Status: —
Size: 0 B
Keys: —
How to use the JSON formatter
- Paste your JSON into the input box (or click "Sample JSON" to try it out).
- Click Beautify for readable 2-space indentation, or Minify for the smallest single-line version.
- Click Validate to check the syntax — if there is an error, you get the exact line and column.
- Copy or download the result as a
.jsonfile.
Common JSON errors this catches
- Trailing commas — a comma after the last item in an object or array (
{"a":1,}is invalid). - Single quotes — JSON requires double quotes around keys and strings.
- Unquoted keys —
{name:"x"}must be{"name":"x"}. - Missing commas or brackets — every item needs a separator and every
{needs a}.
Because the tool runs entirely in your browser, even large API responses format instantly — and your data never leaves your device.
JSON Formatter FAQs
What does a JSON formatter do?
It takes compact or messy JSON and reprints it with clean 2-space indentation so you can read the structure at a glance. It also validates the JSON — if there is a syntax error, it tells you the exact line and column so you can fix it fast.
Is my JSON uploaded to a server?
No. Everything runs locally in your browser with JavaScript. Your JSON is never sent to any server, which makes this safe for API keys, tokens and other sensitive data — though you should still avoid pasting real secrets into any online tool.
What is the difference between beautify and minify?
Beautify adds line breaks and indentation so humans can read the JSON. Minify removes all unnecessary whitespace so the JSON is as small as possible — useful when sending data over the network or storing it in a database. Both keep the exact same data.
How do I fix invalid JSON?
The most common problems are trailing commas after the last item, single quotes instead of double quotes, unquoted keys, and missing commas or closing brackets. Paste your JSON above and the error message will point to the exact line and column where the parser stopped — fix that spot first, then validate again.
Is there a size limit?
There is no hard limit, but very large files (several megabytes) can feel slow because the whole document is re-rendered in the browser. For everyday API responses and config files up to a few hundred kilobytes, formatting is instant.