Beautify, minify and validate JSON instantly.
Updated
Quick start
Paste JSON, pick an indent style, copy the formatted output. Errors point to the exact line + column.
Drop API responses, config files or any JSON snippet into the editor. Enable 'Fix common mistakes' if your source has trailing commas, single quotes or comments.
Choose 2 spaces, 4 spaces, tab indentation, or Minify to strip every optional space for production payloads.
Hit Copy or press ⌘/Ctrl+Enter to grab the formatted output. If parsing fails, the error panel shows the exact line, column and a caret-pointed excerpt.
In-depth guide
Beautify, minify and validate JSON in the browser. Errors show the exact line, column and a caret-pointed excerpt so you can spot the broken comma without scrolling. The "Fix common mistakes" toggle turns almost-JSON (trailing commas, single quotes, JS comments) into the real thing.
JSON (JavaScript Object Notation) is a strict text format derived from a subset of JavaScript object syntax. Six value types: string, number, boolean, null, array, object. Strings are always double-quoted; keys must be strings; no trailing commas; no comments.
It became the default API wire format because it's human-readable, language-agnostic and every modern runtime parses it natively.
The transforms are textual, not parser-aware. Apostrophes inside single-quoted strings, URLs containing // outside strings, or keys that happen to be reserved words can confuse the cleanup. Always re-check the output before saving over the original file.
Toggle the option to enable a best-effort pre-processor that handles the four most common reasons strict JSON.parse rejects almost-JSON:
{ name: "x" }) — keys get wrapped in quotes.// and /* */) — stripped entirely.When the parser fails, we surface three pieces of info:
The most common causes: missing comma between properties, missing closing brace, unescaped double quote inside a string. The structure tile (Depth / Keys / Arrays …) only appears on successful parse — use it as a sanity check that the data shape matches what you expect.
No. Parsing, formatting and validation all run in your browser via the built-in JSON.parse / JSON.stringify functions. Open DevTools → Network during use — you'll see zero requests.
Trailing commas before `}` or `]`, single-quoted strings, unquoted object keys, and `//` line + `/* */` block comments. These transforms are best-effort and lossy in edge cases — use them for permissive paste-and-go, not for production data.
Each browser's JSON.parse reports errors slightly differently. We extract the position from V8's 'at position N' and Firefox's 'line N column M' messages; if neither pattern matches, we show the raw error without coordinates.
Modern browsers can parse JSON in the 100-500 MB range, but the textarea UI becomes sluggish well before that. For multi-megabyte payloads use a code editor with virtualised rendering — this tool is tuned for normal API responses (typically under a few MB).
Yes — ECMA-262 guarantees integer-keyed properties come first in numeric order, then string-keyed properties in insertion order. JSON.stringify follows the same rules, so what you see in the output matches what runtime code would iterate.
Enable 'Fix common mistakes' — `//` and `/* */` comments get stripped before parsing. Note the JSON spec itself forbids comments; the cleaned output won't contain them.
Keep exploring
Hand-picked utilities that pair well with the one you're on — all free, client-side, and zero-signup.
Shrink PDF file size without uploading to a server.
Combine multiple PDFs into one in your browser.
Split a PDF by pages or page ranges, download as zip.
Convert JPG, PNG and WebP into a single PDF, locally.