JSON formatter and validator
Paste JSON to pretty-print or minify it, with parse errors pinpointed by line and column — processed entirely in your browser, nothing uploaded.
0 characters · 0 bytes
Everything runs in your browser — nothing is uploaded.
Find the broken comma in seconds
A trailing comma, a missing bracket, an unescaped quote — JSON fails loudly but rarely tells you where. When an API response, a config file, or a log payload refuses to parse, scanning a minified one-line blob by eye is hopeless, and "Unexpected token" without a location is no help at all.
This formatter validates as you paste. Valid JSON is pretty-printed with consistent indentation — or minified to a single line when you need a compact payload. Invalid JSON gets a precise error with the line and column where parsing failed, so you jump straight to the broken character. Everything runs locally in your browser; API responses and config files never leave your machine.
How to format and validate JSON
- 1
Paste your JSON
Paste an API response, config file, or any JSON blob. Validation runs immediately in your browser.
- 2
Fix errors by line and column
If parsing fails, the error message points to the exact line and column — go straight to the trailing comma or missing bracket and fix it.
- 3
Format or minify, then copy
Choose pretty-print for readability or minify for a compact payload, then copy the result back to your editor or terminal.
JSON formatter FAQ
Is this JSON formatter free?
Yes. It is completely free with no signup and no limits.
Is my JSON uploaded to a server?
No. Parsing, formatting, and minifying all run in your browser with JavaScript. API responses and configs often contain sensitive data — they stay on your machine.
What is the difference between formatting and minifying?
Formatting adds indentation and line breaks so humans can read the structure; minifying strips all whitespace into one line for smaller payloads. Both produce equivalent JSON.
Why does my JSON fail with a trailing comma?
Strict JSON forbids trailing commas, comments, and single quotes, even though JavaScript allows them. The validator follows the JSON spec and points at the exact offending character so you can remove it.
Explore more
Capabilities
By framework
Structured data deserves structured monitoring
If you are formatting JSON to debug a production payload, AllStak can shortcut the trip: log management keeps your structured logs searchable, and error tracking attaches the JSON context to every exception — no copy-paste required.