JSON Formatter & Validator — Free Online Tool
Our free JSON formatter instantly beautifies and validates any JSON string. Paste raw, minified, or broken JSON and get clean, indented output with syntax highlighting in milliseconds. No server uploads — everything runs in your browser.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight data-interchange format used by virtually every web API, configuration file, and database in existence. It's human-readable but can be hard to parse when minified or poorly formatted.
How to use this JSON Formatter
- Paste your JSON into the left panel
- Click Format / Beautify or press Ctrl+Enter
- The formatted, syntax-highlighted result appears on the right
- Use Minify to compress JSON for production use
- Copy the output or download as a .json file
Features
- Real-time JSON validation with precise error messages
- Syntax highlighting for keys, strings, numbers, booleans and null
- 2-space, 4-space, or tab indentation
- JSON minifier for reducing file size
- Object/array depth and key count statistics
- 100% client-side — your data never leaves your browser
Frequently Asked Questions
Is this JSON formatter safe to use with sensitive data? +
Yes. This tool runs entirely in your browser using JavaScript. Your JSON data is never sent to any server. It's safe to use with API keys, database exports, and private configuration files.
Why is my JSON showing an error? +
Common JSON errors include: trailing commas (not allowed in JSON), single quotes instead of double quotes, unquoted keys, missing colons or commas, and undefined/NaN values. The error message will point to the exact line and character position of the problem.
What's the difference between JSON and JavaScript objects? +
JSON is a strict text format derived from JavaScript syntax. Unlike JS objects, JSON requires all keys to be double-quoted strings, does not allow trailing commas, and cannot contain functions, undefined, or comments.
Can I format large JSON files? +
Yes. Since everything runs in your browser, you can format very large JSON files without any upload limits. Performance depends on your device, but files up to several MB format instantly on modern hardware.
How do I minify JSON? +
Click the "Minify" button to remove all whitespace and produce a compact single-line JSON string. This is useful for reducing payload size in API responses and configuration files.