JSON Formatter Online Free
Format, validate, minify JSON. Syntax highlighting, error detection with line numbers. 100% client-side.
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About JSON Formatter, Validator & Beautifier Online
Validate, beautify, and minify JSON with error detection showing line numbers. Custom indent (2 or 4 spaces). All processing is client-side — your JSON never leaves your browser.
JSON is the standard data format for virtually all modern REST APIs, but minified or poorly-formatted JSON returned by an API response is nearly unreadable during debugging — a single missing comma or unclosed bracket can break parsing entirely, and finding it in a wall of unformatted text wastes real development time. This tool re-indents JSON with proper nesting, validates the syntax and reports the exact line number of any error, and can also minify formatted JSON back down for production use where payload size matters. It's built for the everyday workflow of backend and frontend developers who need to quickly inspect, debug, or clean up API responses and config files.
How to use
- Paste or type your input directly into the editor — output updates in real time as you work.
- Check the error/status indicator if your input is invalid; it points to the exact line or issue where relevant.
- Use the copy or download button to grab the processed output once it looks right.
- Chain into a related tool below if your workflow needs a second processing step.
- Processing happens entirely client-side in your browser — nothing you paste is uploaded to a server.
Tool details
⚡ Next step — complete your workflow
Frequently asked questions
Common JSON errors?
Trailing commas after last key/value, single quotes instead of double quotes, unescaped special characters, comments (JSON does not support comments).
JSON vs JSONC difference?
JSON does not support comments. JSONC (used in VS Code configs) allows comments. Our validator is strict JSON.
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