Left
Paste or edit JSON here (source)
Right
Formatted output (also editable)
Validation details
Showing the last validate/format result for Left (source)
No validation errors
Click Validate or Format to re-check the current source pane.
JSON Formatter
Validate JSON, pretty-print it, and optionally standardize key casing — entirely in your browser.
Keep keys as-is
JSON Formatter Features
Our free online JSON formatter and validator provides everything you need to work with JSON data. Whether you're a developer, data analyst, or just need to format JSON for readability, our tool makes it easy.
- ✓JSON validation with detailed error reporting (line, column, code frame)
- ✓JSON formatting and pretty printing with customizable indentation
- ✓Key case conversion (camelCase, PascalCase, snake_case)
- ✓Side-by-side diff viewer to compare original and formatted JSON
- ✓File upload and download support
- ✓Works entirely in browser - no data uploaded to servers
- ✓Real-time syntax highlighting and error detection
- ✓Copy to clipboard functionality
Common Use Cases
API Development
Format and validate JSON responses from APIs to ensure proper structure and catch errors early in development.
Data Analysis
Make large JSON files readable by formatting them with proper indentation, making it easier to analyze data structures.
Code Migration
Convert key names between different naming conventions (camelCase, PascalCase, snake_case) when migrating between systems or frameworks.
Debugging
Use our detailed error reporting to quickly identify and fix syntax errors in JSON files, with line and column numbers for precise error location.
Frequently Asked Questions
What is a JSON formatter?
A JSON formatter is an online tool that validates, formats, and beautifies JSON (JavaScript Object Notation) data. It helps developers make JSON code more readable by adding proper indentation, line breaks, and structure. Our JSON formatter also validates syntax and can convert key names to different casing styles (camelCase, PascalCase, snake_case).
How do I format JSON online?
Simply paste your JSON code into the left editor, click 'Validate & Format', and the formatted JSON will appear in the right panel. You can also upload a JSON file, adjust indentation (2 spaces, 4 spaces, or tabs), and convert key names to different casing formats. The tool works entirely in your browser - no data is uploaded to servers.
Can I validate JSON syntax?
Yes! Our JSON validator checks your code for syntax errors and provides detailed error messages including the exact line and column where issues occur. It also displays a code frame showing the problematic area, making it easy to fix errors quickly.
What is the difference between JSON formatter and JSON validator?
A JSON formatter beautifies and structures your JSON code for readability, while a JSON validator checks if your JSON syntax is correct. Our tool does both - it validates your JSON first, then formats it if valid. If there are errors, it shows detailed validation information instead.
Can I convert JSON keys to camelCase, PascalCase, or snake_case?
Yes! Our JSON formatter includes a key case converter. You can transform all keys in your JSON object to camelCase (userName), PascalCase (UserName), or snake_case (user_name). This is useful when working with different coding conventions or API requirements.
Is my JSON data secure?
Absolutely. Our JSON formatter runs entirely in your browser using client-side JavaScript. No data is sent to any server - everything is processed locally on your device. This means your sensitive JSON data never leaves your computer.
Can I see the differences between original and formatted JSON?
Yes! Click the 'View Diff' button below the editors to see a side-by-side comparison of your original JSON and the formatted version. This helps you understand exactly what changes were made during formatting.
What file formats are supported?
You can upload JSON files (.json) or paste JSON directly into the editor. The formatted output can be downloaded as a JSON file or copied to your clipboard. Our tool also supports XML formatting and validation on a separate page.