JSON Formatter & Validator Online

JSON: The Universal Data Language

JSON (JavaScript Object Notation) is the de-facto standard for data exchange on the web. Virtually every REST API, most configuration files, and all modern databases with schema-less storage use JSON. It's human-readable, language-agnostic, and maps naturally to objects, arrays, and primitives.

📐 JSON Data Types

⚠️ Common JSON Syntax Errors

• Trailing commas: [1, 2, 3,] — valid in JavaScript but illegal in JSON.
• Single quotes: {'key': 'value'} — only double quotes are valid.
• Comments: JSON has no comment syntax. Use a pre-processor like JSONC or JSON5 if you need comments in config files.
• Undefined / NaN / Infinity: these JavaScript values have no JSON equivalent. Serializers typically omit or replace them.
• 64-bit integers: JSON numbers are IEEE 754 doubles, so integers above 2⁵³ lose precision. Use strings for large IDs (e.g. Twitter/X IDs).

🔄 Format vs Minify

Formatting (pretty-print) adds indentation and line breaks — essential for code review, debugging, and config files committed to version control. Minifying removes all whitespace — every byte counts when sending JSON over the wire in high-traffic APIs. For large payloads, also consider gzip compression (which handles repetitive JSON structure extremely well) and binary formats like MessagePack or Protocol Buffers for maximum efficiency.

Your JSON never leaves your browser — all formatting and validation runs locally.