Paste your JSON and format, validate, or minify it instantly online — free, fast, and 100% private. Also supports YAML and XML.
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You paste a wall of minified JSON from an API response. It's one line, 4,000 characters, no whitespace. You need to find why a key is missing. Without a formatter, you're scanning raw text character by character. With this free online JSON formatter, you click Format and the structure is immediately visible — nested objects indented, arrays on separate lines, the problem obvious in seconds.
Format / Prettify — use this when reading or debugging. Adds indentation and line breaks. A 1-line minified payload becomes a readable tree structure.
Minify — use this before sending data over a network. Strips all whitespace. A 4KB formatted JSON file might become 2.8KB minified.
Validate Only — use this when you just need a yes/no on whether the syntax is correct. Shows the exact line and character position of any error.
Copy this sample API response into the formatter to see it in action:
{"user":{"id":4821,"name":"Alice","email":"alice@example.com","roles":["admin","editor"],"settings":{"theme":"dark","notifications":true,"timezone":"UTC-5"}},"token":"eyJhbGciOiJIUzI1NiJ9.payload.signature","expires_at":1735689600}All formatting and validation runs in your browser. Nothing is sent to a server. You can safely paste API keys, credentials, and internal configuration data — it never leaves your device.
The most common causes are trailing commas (JSON doesn't allow them after the last item), single quotes instead of double quotes around strings, or unescaped special characters inside string values. The formatter will show you the exact line and character where the error occurs.
Format (prettify) adds indentation and line breaks to make data human-readable — useful for debugging and reading. Minify removes all whitespace to produce the smallest possible output — useful for production APIs and config files where file size matters.
Yes, but browser performance depends on your device. Files up to a few MB format instantly. Very large files (10MB+) may take a few seconds. Since everything runs in your browser, there's no server-side file size limit.
The JSON tab uses the standard JSON spec, which doesn't allow comments or trailing commas. If your file has comments (like a tsconfig.json or VS Code settings file), you'll need to remove them first.
Yes — all processing happens entirely in your browser. Nothing is sent to any server. You can verify this by opening your browser's network tab while using the tool; you'll see zero outbound requests triggered by your input.