About Format JSON — Online JSON Formatter, Validator & Diff Tool
Format JSON Online — Free JSON Formatter
Format JSON online for free — paste, upload, or fetch JSON data and instantly beautify it into readable, indented code. Minify JSON for production use with one click. All processing happens in your browser — nothing is sent to a server.
JSON Validator
As you type or paste, the editor validates your JSON in real time. Syntax errors are displayed immediately with descriptive messages, helping you quickly locate and fix malformed data like missing commas, unquoted keys, or trailing brackets.
JSON Tree Viewer
Switch to the Tree Viewer tab to explore your data as a collapsible hierarchy. Each node shows the key name, value type, and item count. Click any value to copy it to your clipboard. Use the breadcrumb bar to track your position in deeply nested structures.
JSON Diff — Compare Two JSON Documents
The Diff tab lets you paste two JSON documents side by side and compare them. Differences are highlighted as added (green), removed (red), or changed (yellow) with full path notation, making it easy to spot what changed between API responses or config files.
Export JSON to CSV, YAML, and More
Export your JSON data to multiple formats. Convert arrays of objects to CSV for use in spreadsheets, or transform JSON to YAML for configuration files. Download formatted or minified JSON with one click.
Multiple Ways to Load JSON
Paste JSON directly, drag and drop a .json file onto the page, use the file picker to import from disk, or enter a URL to fetch JSON from any public API endpoint that supports CORS.
Frequently Asked Questions
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format. It is easy for humans to read and write, and easy for machines to parse and generate. JSON is widely used for APIs, configuration files, and data storage.
Is my data safe?
Yes. This tool runs entirely in your web browser. Your JSON data is never transmitted to any server, stored in any database, or shared with third parties. There is no backend — it is a static HTML, CSS, and JavaScript application.
Does it work offline?
Yes. This JSON viewer is a Progressive Web App (PWA). After your first visit, it is cached by a service worker and works without an internet connection. You can even install it as a standalone app on desktop or mobile.
What browsers are supported?
All modern browsers: Chrome, Firefox, Safari, Edge, and Opera. The app uses standard web APIs and has no external dependencies.
How do I format JSON?
Paste your JSON into the editor and click the Format button in the toolbar, or press Ctrl+Shift+F. The JSON will be reformatted with 2-space indentation.
How do I minify JSON?
Click the Minify button or press Ctrl+Shift+M to remove all whitespace and produce the most compact JSON representation.
Can I search inside JSON?
Yes. In the Tree Viewer tab, use the search bar to find keys or values. Results are highlighted and you can navigate between matches with the arrow buttons.