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 the de facto standard for APIs, configuration files, and data storage across the web.
Why Format JSON?
Raw JSON from APIs or logs is often minified — a single long line with no whitespace. Formatted (or "pretty-printed") JSON adds indentation and line breaks, making the structure immediately visible. This helps developers debug faster, spot missing brackets, and understand nested data at a glance.
Features of This Tool
- Instant formatting with 2-space or 4-space indentation
- Real-time validation as you type — catch errors before they break your code
- One-click minification to reduce payload size
- Syntax highlighting — keys, strings, numbers, booleans, and null each get a distinct color
- 100% client-side — your data never leaves your browser
- Works on mobile, tablet, and desktop
Common JSON Errors
The most frequent mistakes in JSON are trailing commas (not allowed), single quotes instead of double quotes, unquoted keys, and missing closing brackets. This validator highlights the exact position of errors so you can fix them quickly.