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Free online tool
Format, validate, and minify JSON data — instantly in your browser.
Privacy: All processing happens in your browser. No data is stored or sent to any server.
A JSON formatter is a developer tool that takes raw or minified JSON (JavaScript Object Notation) and transforms it into a human-readable, indented format. JSON is the universal data interchange format used by REST APIs, configuration files, databases, and virtually every modern web service. Reading minified or compressed JSON is nearly impossible for humans — a formatter adds consistent indentation, line breaks, and syntax highlighting so you can quickly understand, debug, and edit the data structure. This tool also validates JSON syntax and can minify formatted JSON back into its most compact form for production use.
The tool uses JavaScript's native JSON.parse() to read your input and detect any syntax errors. If the JSON is valid, JSON.stringify() is called with your chosen indentation level (2 spaces, 4 spaces, or tabs) to produce a pretty-printed output. For minification, it calls JSON.stringify() with no indentation, stripping all unnecessary whitespace. Validation parses the input and reports the first syntax error with its character position. Because these are built-in browser APIs, the entire process runs locally without any server-side processing — your data never leaves your device.
You receive a minified API response and need to inspect its nested structure to debug a missing field.
A previously unreadable 2,000-character JSON blob is now clearly indented and easy to navigate, saving you minutes of manual formatting.
No. All processing happens entirely in your browser using JavaScript's built-in JSON.parse() and JSON.stringify(). Nothing is transmitted over the network.
It works well with files up to several megabytes. Very large files (10 MB+) may cause the browser to slow down temporarily.
It checks whether your input is syntactically valid JSON and reports the first error with its position if not.
This tool parses standard JSON (RFC 8259). JSONL files should be split line by line, and JSON5 must be converted to standard JSON first.
No. Formatting and minification only change whitespace and indentation. The data values, keys, and structure remain identical. JSON.parse(formatted) === JSON.parse(minified).
Whether you are debugging an API response, editing a configuration file, or preparing data for a colleague, a JSON formatter is an indispensable tool in every developer's workflow. This free JSON Formatter & Validator runs entirely in your browser, keeping your data private while giving you instant formatting, validation, and minification with zero setup.