What is JSON Formatter?
JSON Formatter is a secure, fast, and free online tool that helps developers parse, format, validate, and beautify JSON data. All processing happens locally in your browser, ensuring 100% privacy for your sensitive data.
Key Features
- JSON Beautifier & Formatter: Make unreadable, minified JSON code well-structured and easy to read.
- Compact Format: Compress primitive-value objects and arrays into single lines while keeping complex structures indented, balancing readability and conciseness.
- Partial Format: In compact mode, click the partial format button next to a node to expand only that object or array individually โ no need to expand everything at once, perfect for navigating complex nested structures.
- Syntax Validator & Auto-fix: Instantly detect errors and automatically fix BOM characters, single quotes, Python-style booleans and nulls (True/False/None/NULL), unquoted keys, trailing commas, and missing commas.
- Format Conversion: Easily convert JSON to XML or YAML with a single click.
- Double-click to Copy: Double-click a Key to copy the key name, double-click a Value to copy the value, or double-click an entire row to copy the current line โ with a visual highlight on success.
- Smart Filtering: Supports plain text search, regex filtering (e.g.,
/pattern/i), and numeric comparison (e.g., >10, <=100) to quickly locate target data.
- 5 Theme Skins: Choose from Light, Dark, Monokai, Solarized Light, and Dracula themes to suit different environments and personal preferences.
- Compress & Restore: One-click compress formatted JSON into a single line, or restore it to the original formatted state at any time.
- Undo Support: Press Ctrl+Z to undo changes in the input area, making it easy to revert accidental edits.
- Font Size Adjustment: Choose from Small (12px), Medium (14px), or Large (16px) to fit different screens and reading preferences.
- File Upload & Download: Upload local JSON files for parsing, or download the formatted result as a file.
- Node Expand & Collapse: Expand or collapse individual nodes, or use the expand-all / collapse-all buttons for easy navigation of large JSON structures.
- Offline Support: Works entirely in your browser with no server uploads required โ 100% data privacy.
Frequently Asked Questions (FAQ)
Is my JSON data secure?
Yes! This tool is a pure client-side application. Your JSON data is never uploaded to any server. All formatting and validation happen directly within your browser.
Can it handle large JSON files?
Absolutely. Our parser is optimized to handle large JSON datasets efficiently without crashing your browser tab.
What is compact format?
Compact format compresses primitive-value objects and arrays into single lines while keeping complex structures indented. It balances readability and conciseness, making it easier to scan large JSON structures.
What syntax errors can be auto-fixed?
The auto-fix feature handles: BOM characters, single quotes converted to double quotes, Python-style booleans and nulls (True/False/None/NULL), unquoted keys, trailing commas, and missing commas.
How do I copy a specific Key or Value from the JSON?
Simply double-click on any Key text to copy the key name, or double-click on any Value to copy its value. A brief highlight and toast notification will confirm the copy. To copy an entire row, double-click on the empty area of that row.
What is Partial Format and how do I use it?
Partial Format is a feature available in compact mode. After applying compact formatting, a partial format button appears next to each object or array node. Click it to expand only that specific node while keeping everything else compact โ perfect for exploring deeply nested JSON structures layer by layer.
How do I switch theme skins?
Click the theme switch button (palette icon) in the top-right corner to cycle through Light, Dark, Monokai, Solarized Light, and Dracula themes. Your selection is automatically saved in the browser and will be applied on your next visit.
What syntax does the filter support?
The filter input supports three modes: 1) Plain text search โ type a keyword to match nodes containing that text; 2) Regular expressions โ enter in /pattern/flags format, e.g., /user/i for case-insensitive matching; 3) Numeric comparison โ use operators like >N, <N, >=N, <=N, =N to filter numeric value nodes.