Format, beautify, and validate JSON data instantly. Our free online tool processes everything locally in your browser, ensuring your data stays private and secure.
Copy your unformatted, minified, or messy JSON data and paste it into the input field on the left. The tool accepts any valid JSON including objects, arrays, strings, numbers, booleans, and null values.
Select your preferred indentation level: 2 spaces (common in web development) or 4 spaces (common in enterprise applications). The choice is purely stylistic and doesn't affect the JSON data itself.
Click "Format" to beautify your JSON with proper indentation and line breaks, or click "Minify" to remove all whitespace for a compact version. Use keyboard shortcuts for faster workflow: Ctrl+Enter to format, Ctrl+Shift+M to minify.
Once formatted, use the "Copy" button to copy the result to your clipboard, or click "Download" to save it as a .json file. The file will be named "formatted.json" by default.
Our JSON formatter uses a multi-stage parsing and formatting engine built entirely in JavaScript, ensuring all processing happens locally in your browser. No data is ever sent to our servers, maintaining complete privacy and enabling offline functionality.
Validates syntax using the native JSON.parse() method. Checks for correct bracket and brace matching. Verifies proper quote usage (double quotes for keys and strings). Detects invalid escape sequences. Identifies missing or extra commas. Reports trailing commas (invalid in standard JSON).
After successful parsing, the formatter reconstructs the JSON string using JSON.stringify() with custom spacing parameters. You can configure indentation to use either 2 or 4 spaces. The formatter preserves the original data types and structure while adding proper whitespace for readability.
If JSON.parse() encounters an error, we capture the error message and parse it to pinpoint the exact line and character position of the syntax error. This information is displayed with helpful context to guide you toward fixing the issue quickly.
This tool includes an automatic repair feature powered by the jsonrepair library. It can fix many common JSON issues including: trailing commas, unquoted keys, single quotes instead of double quotes, and missing quotes around keys. When auto-repair is applied, you'll see a notification indicating the JSON was fixed.
Optimal performance for files up to 10MB; larger files may cause browser lag. Very large JSON files (>50MB) may exceed browser memory limits. Requires JavaScript ES6+ support (all modern browsers). Comments in JSON are not supported and will cause errors.
This tool follows the JSON specification defined in RFC 8259 (The JavaScript Object Notation Data Interchange Format, December 2017) and ECMA-404 (2nd edition, December 2017). All parsing and serialization uses the native browser JSON implementation for maximum compatibility and performance. Standards last verified: February 2026.
Input: {name: 'John', age: 30} Steps: 1. Auto-repair detects unquoted keys and single quotes 2. Repairs to valid JSON: {"name": "John", "age": 30} 3. Parses and validates structure (object with 2 keys) 4. Formats with selected indentation (2 spaces) Output: { "name": "John", "age": 30 } The auto-repair feature automatically fixed the syntax issues, allowing you to format non-standard JSON input.
All the formatting — indentation, syntax checking, minification — runs in JavaScript right in your browser. Your JSON doesn't go anywhere. We chose client-side processing because developers often paste config files containing API keys and connection strings, and we didn't want to handle that.
Saved Presets is a Supporter feature.
Tool History is a Supporter feature.
Tool Notes is a Supporter feature.
