Paste any JSON to instantly format it with clean indentation, validate its structure, and catch syntax errors with a clear line number — plus a one-click minify option and syntax-highlighted output. Built for developers debugging API responses and config files.
Reading unformatted JSON — especially a minified API response — is painful. This tool takes any JSON you paste in, formats it with two-space indentation, and applies colour-coded syntax highlighting so keys, strings, numbers and booleans are easy to tell apart at a glance.
If your JSON has a syntax error, the tool tells you exactly what went wrong and roughly which line it happened on, instead of leaving you to hunt through a wall of text manually.
Step 1 — Paste your JSON. This can be an API response, a config file, or anything you're debugging.
Step 2 — Click Format & Validate. Valid JSON is instantly pretty-printed with syntax highlighting. Invalid JSON shows a clear error message with an approximate line number.
Step 3 — Minify when you're done. Once your JSON is correct, use Minify to strip all whitespace for production use, then copy the result.
Trailing commas. Unlike JavaScript objects, JSON doesn't allow a trailing comma after the last item in an array or object — this is one of the most common errors.
Using single quotes. JSON strings and keys must use double quotes. Single quotes will cause a parse error.
Forgetting to close brackets. A missing closing `}` or `]` produces an "unexpected end of JSON input" error — check that every opening bracket has a matching close.
The most common causes are trailing commas, single quotes instead of double quotes, or an unclosed bracket. The error message and line number point you to roughly where to look.
Formatting adds indentation and line breaks to make JSON readable. Minifying removes all unnecessary whitespace to make the file as small as possible — useful for production APIs.
No. All parsing, formatting and validation happens locally in your browser using the built-in JSON parser — nothing is uploaded.
Yes, though very large files (several megabytes) may format more slowly since everything runs in the browser rather than on a server.
JSON is the backbone of most web APIs, but raw or minified JSON is hard to read and debug. A quick format-and-validate pass saves time when tracing down malformed API responses, broken config files or messy copy-pasted data.