JSON Formatter & Validator
Paste or upload JSON to format, minify and validate it instantly in your browser. Syntax errors include line and column numbers.
All processing happens locally in your browser. Nothing is uploaded.
Paste or upload JSON to format, minify and validate it instantly in your browser. Syntax errors include line and column numbers.
All processing happens locally in your browser. Nothing is uploaded.
The JSON Formatter & Validator tool beautifies, minifies, and checks JSON for syntax errors. Formatting runs in your browser, so your data stays private.
Developers use it to make minified JSON readable, catch a missing comma or bracket before deployment, and shrink JSON for production — all in one place.
JSON is the lingua franca of modern web APIs and configuration files, but it is almost always transmitted in a minified single-line form that is unreadable to humans. Formatting (beautifying) that minified JSON with proper indentation turns a wall of text into a structured, scannable document where you can see the nesting, spot the keys, and find the values at a glance.
The tool also validates your JSON, catching the syntax errors that break APIs before you deploy — a missing comma, an unquoted key, a trailing bracket — and reporting the first error it finds with its location so you can fix it. Minify mode does the reverse, stripping all whitespace to produce the smallest possible JSON for production transmission.
JSON formatting and validation run entirely in your browser using the native JavaScript JSON parser. When you paste JSON and choose to format, the tool parses the string into a JavaScript object and re-serialises it with the indent size you selected (2 spaces, 4 spaces, or tabs). For validation, it parses the string and reports the first syntax error with its position. For minify, it re-serialises with no whitespace.
Your data never leaves your device — there is no upload, no server-side processing, and no copy retained after you close the tab. The formatting and validation are instant because they operate on the string in memory. The tool follows standard JSON, which does not allow comments or trailing commas, so remove them before formatting.
For indent size, select 2 spaces, 4 spaces, or tab indentation to match your project style. For related developer tools, use the Base64 Encoder to encode JSON for transport, the QR Generator to share data as a scannable code, and the Word Counter to measure payload size.