JSON Formatter & Validator
Free online JSON formatter, prettifier, minifier, and validator. Runs entirely in your browser. There will be no data is sent to ours or any server.
100% private
No data leaves your browser.
Real-time validation
Errors shown instantly as you type.
Load JSON files
Drag & drop or click to open a .json file.
Frequently Asked Questions
It parses your raw JSON text, checks that it is structurally valid, then re-serializes it either as indented human-readable output (prettify) or as a compact single-line string (minify). Syntax highlighting colors nested keys, string values, numbers, booleans, and null so the structure is easy to scan.
JSON has strict rules: keys must be double-quoted strings, trailing commas are not allowed, comments are not supported, and values must be one of string, number, boolean, null, array, or object. Common mistakes include single-quoted strings, JavaScript-style comments, and trailing commas after the last item in an object or array.
No hard limit is enforced by this tool. Very large files (above roughly 5-10 MB) may be slow to parse and syntax-highlight because JavaScript processes everything on the main thread. For large files, a command-line tool like jq is much faster.
No. Parsing, validation, and formatting all run inside your browser. Nothing leaves your device. The tool works completely offline once the page has loaded.
Yes. Drag and drop a .json file onto the input area or use the file picker. The file is read locally by the browser File API and is never uploaded anywhere.