JSON Formatter Online – Format, diff & fix JSON without uploading anything

Summary: JSON Formatter Online is a browser-based tool that formats, validates, compares, auto-fixes, minifies JSON, and generates TypeScript interfaces without transmitting data. It highlights syntax errors with exact line and column details and supports side-by-side JSON comparison with smart diff.

What it does

The tool formats and beautifies JSON with customizable indentation, validates syntax with precise error locations, compares two JSON files using semantic diff, auto-fixes common errors, minifies JSON, and generates TypeScript interfaces—all client-side.

Who it's for

It is designed for developers working with API responses, config files, and debugging JSON payloads who require privacy and local processing.

Why it matters

It eliminates the need to upload sensitive JSON data by processing everything in the browser, ensuring privacy and security.