The JSON formatter that doesn't phone home
Format, validate, and minify JSON without leaving your browser.
Web Workers keep the editor responsive even with large payloads. The AST parser catches errors the moment they appear.
Deterministic Formatting & Structural Validation
- Deterministic Formatting: Auto-indent to strict RFC-8259 standards using 2 spaces, 4 spaces, or Tabs. Transforms single-line payloads even 100MB+ into strict tree structures via off-main-thread Web Workers.
- AST-Based Validation: Real-time syntax error mapping. Catches trailing commas, missing quotes, and structural anomalies before they reach production.
- Client-Side Minification: Zero-latency whitespace stripping for network-optimized payloads. Includes alphabetical key-sorting for dataset diffing.
Privacy First: Zero-Server Architecture
Format API responses, config files, and credentials without exposing them to third-party services.
FAQ
How do I format JSON?
JSON formatting takes minified or unstructured JSON and applies consistent indentation with line breaks at each nesting level. The result is a human-readable structure where object keys, array contents, and nested values are visually aligned. Most formatters also validate syntax and highlight errors inline.
Why is my JSON invalid?
The most common causes of invalid JSON are trailing commas, missing quotes around keys, or using single quotes instead of double quotes. A strict JSON validator will parse your syntax and highlight the exact line and character where the structure breaks.
Can you put comments in JSON?
No, the official JSON specification (RFC 8259) does not support comments. Including comments in JSON will cause a parsing error. Formats like JSON5 and JSONC do support comments, but they are not valid JSON and require a parser that explicitly handles them.
How do I format a massive JSON file without crashing?
Large JSON files can freeze a browser tab when processed on the main thread. Web Workers solve this by offloading parsing to a background thread, keeping the interface responsive while the formatter processes multi-megabyte files.
What is JSON pretty printing?
JSON pretty printing is the process of converting minified or compact JSON into a human-readable format with proper indentation, line breaks, and spacing. A formatter applies consistent indentation to each nesting level, making it easy to visually parse object structure, array contents, and key-value pairs.