UD5 Toolkit
JavaScript Beautifier & Formatter - Online JS Code Styler
Make your JavaScript code more readable with this online beautifier. Format and indent JS automatically. Works entirely in your browser, protecting your code privacy.
Code Syntax Highlighter - Online Beautiful Code Preview
Code Syntax Highlighter
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Frequently Asked Questions
What is a Code Syntax Highlighter?
A code syntax highlighter is a tool that formats source code using colors and styles to distinguish keywords, variables, strings, comments, and other elements â making code easier to read, understand, and present beautifully.
Which programming languages are supported?
This tool supports 20+ popular languages including JavaScript, TypeScript, Python, Java, C++, C#, Go, Rust, PHP, Ruby, Swift, Kotlin, SQL, HTML/XML, CSS, JSON, YAML, Markdown, Bash, and more. You can also use Auto Detect mode to let the highlighter guess the language automatically.
How many themes are available?
We offer 10 carefully selected themes â a mix of light and dark options. Popular choices include Atom One Dark, GitHub Dark, Monokai, Dracula, Nord, and Tokyo Night. Themes can be switched instantly from the toolbar.
Can I toggle line numbers on/off?
Yes! Click the button in the toolbar to show or hide line numbers in the preview panel. Line numbers are especially useful when sharing code snippets with colleagues or during code reviews.
Is my code stored or sent anywhere?
No. All processing happens entirely in your browser. Your code never leaves your device, ensuring complete privacy and security. This tool works offline after the initial page load.
How do I copy the highlighted code?
Click the Copy button to copy the plain text source code to your clipboard. If you want the raw highlighted HTML, you can inspect the preview panel. The copy feature uses the modern Clipboard API with a fallback for older browsers.
Can I adjust the font size?
Absolutely! Use the + and â buttons in the toolbar to increase or decrease the font size (range: 10pxâ24px). Both the editor and preview panels update simultaneously for a consistent experience.
Does this tool work on mobile devices?
Yes, the tool is fully responsive. On tablets and smartphones, the editor and preview panels stack vertically for easy scrolling and editing. All toolbar controls remain accessible with touch-friendly buttons.
What makes a good syntax highlighting theme?
A good theme provides sufficient contrast between text and background, uses distinct colors for different token types (keywords, strings, comments, numbers), and reduces eye strain during long coding sessions. Our dark themes are optimized for low-light environments.
Is this tool free to use?
Yes, this Code Syntax Highlighter is 100% free with no registration, no ads, and no usage limits. It's built for developers who need a quick, beautiful way to preview and share formatted code snippets.
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Interactively apply CSS filter functions (blur, brightness, contrast, etc.) to an image and copy the resulting filter property. No coding required.