Overview
What this tool does
JSON is the format that almost every modern API, configuration file, and structured-data payload uses. This tool does the three things you almost always need: format (pretty-print with consistent indentation), minify (strip every byte of whitespace for smallest transmission size), and validate (check that the input is well-formed JSON and surface the exact position of any error). Side-by-side input and output panels. Parse errors are reported with line and column numbers so you can jump straight to the problem instead of squinting at "unexpected token at position 1473." Output byte counts compare to input so you can see the compression ratio at a glance. Runs entirely in your browser using the native JSON parser; no upload, no signup, no daily limit.
How to
Use it in 3 steps
- Paste JSON into the Input pane on the left (or click 'Load sample' to try it).
- Pick an indent (2 spaces, 4 spaces, or tab) for formatted output.
- Click 'Format' for pretty-printed output, 'Minify' for the smallest possible single-line version, or 'Validate' to just check well-formedness.
- If the JSON is invalid, an error banner shows what's wrong and where (line + column).
- Copy the output to your clipboard or download it as a .json file.
FAQ
Frequently asked questions
▶Does it support JSONC (JSON with comments) or JSON5?
No. This tool uses the strict JSON spec via the browser's native JSON.parse. Comments, trailing commas, single-quoted strings, and unquoted keys will all be rejected. If you need JSONC support, strip the comments first or use a JSONC-aware parser.
▶Is my data uploaded?
No. Parsing happens entirely in your browser. The text you paste never reaches a server.
▶How big can the input be?
Constrained by your browser's memory. Files up to a few MB parse and format in milliseconds. Very large JSON (50+ MB) may stall the UI briefly while the parser runs synchronously.
▶Why does Minify reorder my object keys?
It doesn't. JSON.stringify preserves the order of properties as they appear in the source. If keys look reordered, the original parse step or your editor's auto-format may have changed them.
▶What's the byte-count percentage in the output footer?
The percentage of size reduction (green) or increase (amber) compared to the input. Useful when you want to see how much smaller a minified version is than the original, or how much overhead pretty-printing added.
▶Can it format nested objects 20 levels deep?
Yes. JavaScript engines handle deeply-nested objects fine for practical sizes. Pathological depths (10,000+ levels) hit the parser's recursion limit, but you'll never run into that with real data.