How to Format JSON Online
- Paste your JSON — Paste raw JSON into the input area. The tool auto-detects and validates it as you type.
- Click Format — Or press
Ctrl+Enter. Your JSON is instantly formatted with proper indentation and syntax highlighting. If there are errors, you'll see exactly where.
- Copy the result — Click "Copy" to copy the formatted output to your clipboard, or "Use as Input" to continue editing.
Features
- Format / Beautify — Pretty prints JSON with your choice of indentation (2 spaces, 4 spaces, or tabs).
- Validate — Instantly checks if your JSON is valid. If not, shows the error type and approximate position so you can fix it.
- Minify — Removes all unnecessary whitespace to create the most compact JSON possible. Useful for APIs and config files.
- Syntax Highlighting — Color-coded output: keys, strings, numbers, booleans, and null values each get distinct colors for easy reading.
- Stats — Shows the size, line count, number of keys, and nesting depth of your JSON.
Common JSON Errors
- Missing commas — Every item in an array or object must be separated by a comma. A missing comma between
"name": "John" and "age": 30 will cause a parse error.
- Trailing commas — JSON does not allow a comma after the last item in an object or array.
{"a": 1,} is invalid.
- Single quotes — JSON requires double quotes around strings and keys.
{'name': 'John'} is invalid; use {"name": "John"}.
- Unquoted keys — All object keys must be double-quoted.
{name: "John"} is invalid.
- Comments — JSON does not support comments. Remove any
// or /* */ comments.
JSON Format vs. Minify
Formatted JSON has indentation and line breaks, making it easy for humans to read and debug. Use formatted JSON during development, in documentation, and when reviewing data structures.
Minified JSON removes all whitespace, reducing file size. Use minified JSON in production APIs, configuration files, and anywhere data size matters. A 50 KB formatted JSON file might minify to 30 KB or less.
Privacy & Security
Unlike many online JSON tools that send your data to a server for processing, FilePulp formats and validates JSON entirely in your browser. Your API responses, configuration files, and data structures are never transmitted anywhere. This is particularly important when working with sensitive data like API keys, user records, or internal system configurations.
Frequently Asked Questions
Is this JSON formatter free?
Yes, completely free. No sign-up, no hidden fees. Format and validate as much JSON as you need.
Is my data uploaded to a server?
No. All formatting and validation happens locally in your browser using JavaScript's native JSON.parse() and JSON.stringify(). Your data never leaves your device — we never see, store, or have access to your JSON.
What does this tool do?
It formats (pretty prints) JSON with proper indentation and syntax highlighting, validates JSON and shows exactly where errors are, and minifies JSON by removing whitespace. You can choose between 2-space, 4-space, or tab indentation.
How do I fix invalid JSON?
When your JSON is invalid, the tool shows the error type and approximate position. Common issues include missing commas between items, trailing commas after the last item, unquoted property names (keys must use double quotes), single quotes instead of double quotes, and comments (JSON doesn't support them).
What's the difference between format and minify?
Format (beautify) adds indentation and line breaks to make JSON human-readable. Minify removes all unnecessary whitespace to make JSON as compact as possible — useful for APIs, configuration files, and reducing payload size.
Is there a size limit?
There is no hard limit. The tool runs entirely in your browser, so performance depends on your device. It comfortably handles JSON files up to several megabytes. For very large files (10MB+), formatting may take a moment.