Free Online JSON Formatter & Validator
Paste your JSON data below to format, validate, or minify it instantly. Everything runs in your browser — your data never leaves your machine.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. It is based on a subset of JavaScript and is commonly used for APIs, configuration files, and data storage.
How to Use This JSON Formatter
- Paste your raw JSON into the input field on the left.
- Click Format (or press
Cmd/Ctrl + Enter) to beautify it. - Choose your preferred indentation: 2 spaces, 4 spaces, or tabs.
- Click Copy to copy the formatted result to your clipboard.
- Use Minify to compress JSON by removing whitespace.
Frequently Asked Questions
Is my data safe?
Yes. This tool runs entirely in your browser using JavaScript. No data is sent to any server. Your JSON stays on your machine.
What makes this JSON formatter different?
OnlineDevTool's JSON formatter is designed for developers. It features dark mode, keyboard shortcuts, instant validation, and a clean distraction-free UI.
Can I format large JSON files?
Yes. The formatter handles large JSON payloads efficiently in your browser. For extremely large files (10MB+), performance will depend on your device.