Free Developer Tool
JSON Formatter & Validator
Paste any JSON to instantly beautify, format, and validate it. Errors are caught with line numbers. Your data never leaves your browser.
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Common JSON Errors
| Error | Cause | Fix |
|---|---|---|
| Unexpected token | Missing comma or bracket | Add missing , or close bracket |
| Unexpected end of JSON | Unclosed string or object | Check all { } [ ] are matched |
| Expected property name | Trailing comma after last item | Remove the last comma |
| Invalid escape character | Unescaped backslash in string | Use \\ instead of \ |
| Unexpected token ' | Single quotes used for strings | Replace all ' with double quotes " |
JSON formatting tips
Always use double quotes for keys and string values
No trailing commas after the last item in arrays or objects
Use 2-space indent for APIs, 4-space for readability
Minify JSON before sending in API requests to reduce payload size
null, true, false must be lowercase with no quotes
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