JSON Formatter & Validator
Valid JSON
What is a JSON formatter?
A JSON formatter takes raw, often unreadable JSON — such as a minified API response — and re-indents it with consistent spacing and line breaks so it's easy for a human to read. This tool also validates that the JSON is syntactically correct, and if it isn't, tells you exactly where the problem is.
When would I use this?
- Debugging an API response that comes back as a single unreadable line.
- Validating a JSON config file before committing it, to catch a missing comma or bracket.
- Minifying a JSON payload to reduce its size before sending it over the network.
- Quickly inspecting the shape/structure of a JSON object nested several levels deep.
How it works
Everything runs using your browser's built-in JSON.parse and JSON.stringify. No part of your input is sent to a server, so it's safe to paste JSON containing real data.
Frequently asked questions
No. All formatting, validation, and minification happens entirely in your browser using JavaScript. Your JSON never leaves your device, which makes this safe to use with real, sensitive data.
It checks for valid JSON syntax per the JSON specification (RFC 8259) — matching brackets and braces, properly quoted keys, valid value types, and correct comma placement — and reports the exact line and character of the first error found.
Yes, use the "Minify" button to collapse the formatted JSON into a single compact line with no extra whitespace, ideal for production payloads.
Yes, the formatter runs natively in your browser's JavaScript engine and can comfortably handle large documents. Extremely large files (tens of MB) may be slower depending on your device.