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Format, beautify, and validate JSON instantly with this free online tool. Paste messy JSON from APIs, config files, or databases and get clean, readable output with proper indentation and syntax highlighting. All processing happens in your browser — your data never leaves your device.
JSON (JavaScript Object Notation) is a lightweight data interchange format that's easy for humans to read and write, and easy for machines to parse and generate. It's the standard format for API responses, configuration files, and data storage in modern web development. JSON supports strings, numbers, booleans, arrays, objects, and null values, making it versatile for representing structured data.
Working with JSON in your code? Here's how to parse and format JSON in popular languages:
Paste your JSON into the input panel on the left. The tool automatically formats and validates it in real-time, showing the beautified output on the right with proper indentation and syntax highlighting. You can adjust the indent size (2 spaces, 4 spaces, or tabs) using the toolbar options.
Formatting (or beautifying) adds proper indentation and line breaks to make JSON readable, while validation checks if the JSON syntax is correct. This tool does both simultaneously — if your JSON has syntax errors, you'll see a detailed error message with the line number and position.
Yes. When the tool detects fixable errors (like trailing commas, missing quotes, or single quotes instead of double quotes), a "Fix & Format" button appears. Click it to automatically repair common JSON issues. You can always undo the fix if needed.
Common causes include: trailing commas after the last item, single quotes instead of double quotes, unquoted property names, missing commas between items, comments (JSON doesn't support comments), and special characters that need escaping. This tool shows the exact line and position of errors to help you fix them quickly.
JSON is preferred for web APIs, JavaScript applications, and when you need lightweight data interchange. It's more compact and easier to parse than XML. Use XML when you need document markup, namespaces, schemas (XSD), or when working with legacy systems that require it. Most modern REST APIs use JSON.
Yes. All formatting and validation happens entirely in your browser using JavaScript. No JSON data is ever sent to any server. Your input is saved in your browser's localStorage for convenience, but you can clear it anytime.
You can choose between 2 spaces (default), 4 spaces, or tabs for indentation. Use the dropdown in the toolbar to switch. Your preference is saved automatically for future sessions. You can also minify JSON to remove all whitespace.
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