JSON Formatter
Validate · Transform · Explore
100% Client-Side & Secure
Your data never leaves your device. All JSON validation, beautification, minification, URL encoding, tree exploration, and diff comparison execute entirely within your browser's local memory. No input is sent to, stored on, or logged by any external server—making this tool safe for proprietary API payloads, configuration secrets, and production data.
JSON Syntax Reference
Strict JSON differs from JavaScript object literals. Use this quick reference to spot the most common syntax mistakes before they trigger parse errors.
| Data Type | Valid Syntax Example | Common Pitfall / Invalid Example |
|---|---|---|
| Strings | "hello world" | 'hello world'JSON requires double quotes for string values; single quotes are invalid. |
| Trailing Commas | ["a", "b", "c"] | ["a", "b", "c",]Arrays and objects cannot end with a trailing comma before the closing bracket. |
| Object Keys | { "id": 1, "name": "Alice" } | { id: 1, name: 'Alice' }Every object key must be wrapped in double quotes—unquoted keys are JavaScript, not JSON. |
| Numeric Types | 42, -3.14, 1.5e10 | 01, 007Leading zeros are not permitted; numbers must follow standard JSON numeric syntax. |
Frequently Asked Questions
Answers to common questions about JSON formatting, performance, and privacy.
Official Documentation
For authoritative definitions of JSON syntax and browser APIs, consult these primary references: