Free Online JSON Formatter & Validator
Beautify, minify, and validate JSON online with syntax highlighting and error line detection. Free, 100% client-side — your data never leaves your browser.
100% Client-Side · Your data never leaves your browserHow to Use JSON Formatter & Validator
Paste your JSON into the Input panel on the left. Choose a mode:
- Beautify — formats the JSON with readable indentation and syntax highlighting. Select 2 spaces, 4 spaces, or tab indentation.
- Minify — strips all whitespace for the most compact valid JSON output.
Click the mode button or press Ctrl/Cmd+Enter to process. If your JSON contains a syntax error, the error message will include the approximate line number. Use Copy to copy the full output to your clipboard.
Frequently Asked Questions
What is JSON beautification?
JSON beautification (pretty-printing) adds whitespace, line breaks, and consistent indentation to compact or minified JSON, making it readable. The raw data is identical — only the formatting changes.
What does "minify JSON" mean?
Minifying removes all unnecessary whitespace and newlines from JSON, producing the most compact valid representation. This reduces file size and is useful before transmitting JSON over a network or storing it in a database.
What happens if my JSON has an error?
The formatter will show an error message including the approximate line number where the syntax error was detected. Common issues include trailing commas, unquoted keys, and mismatched brackets.
Is my data uploaded to a server?
No. All JSON processing happens in your browser using the built-in JavaScript JSON.parse and JSON.stringify APIs. Nothing is sent to any server.
What indentation options are available?
You can choose 2 spaces (default), 4 spaces, or a tab character. This only affects the beautified output — minified output has no indentation by definition.
Can this tool handle large JSON files?
Yes, within browser memory limits. For very large outputs (over 50,000 characters), the displayed preview is truncated, but the Copy button gives you the complete result.