Type code to see highlighting...This code syntax highlighter is simple yet powerful. Here is a detailed guide:
Paste your code: Paste the code snippet you want to highlight into the left input box. You can copy code from any editor, IDE, or webpage and paste it directly without any preprocessing.
Select language: Choose the programming language from the dropdown menu. If "Auto Detect" is enabled, the tool will automatically infer the language type based on code content (e.g., file extensions, common syntax patterns). Currently supports JavaScript, HTML, CSS, Python, SQL, JSON, XML, Bash, PHP, Java, C, C++, Go, Rust, TypeScript, YAML, Markdown, and more.
View highlighting: After selecting the language, the right preview area will display syntax-highlighted code in real time. Keywords, strings, comments, numbers, and more are color-coded, making it easy to read and understand the code structure.
Line number control: Toggle "Show Line Numbers" to control whether line numbers appear in the preview. Turning them off is useful for screenshots or pasting into documents.
Export HTML: Click the "Export HTML" button to download the highlighted code as a self-contained HTML file with inline CSS styles. You can embed it directly into web pages, blogs, or technical documentation without external dependencies.
Code syntax highlighting is widely used across many scenarios:
Technical blogging: When writing technical blog posts, use this tool to generate syntax-highlighted code snippet HTML and embed it directly into your articles. Compared to plain text code, highlighted code is much easier for readers to understand and significantly improves the professionalism and readability of your content.
Code sharing and discussion: When collaborating with teammates or discussing in communities, share your code after highlighting it. This helps colleagues or community members quickly locate key logic and reduces communication overhead. Especially during code reviews, highlighted code makes issues easier to spot.
Teaching and presentations: Teachers and technical instructors can use this tool to create beautiful code examples for course materials or presentations. Syntax highlighting helps students quickly distinguish keywords, variables, comments, and more, improving learning outcomes.
Documentation writing: When writing API docs, technical specifications, or project READMEs, embed highlighted code examples to significantly improve readability and professionalism.
How syntax highlighting works: Syntax highlighting uses lexical analysis to break code text into tokens, then applies different colors and styles based on token types (keywords, strings, comments, etc.). This tool uses regular expressions for lexical analysis, assigning CSS class names to different token categories, with CSS defining the display style for each token type.
History of syntax highlighting: The earliest syntax highlighting appeared in text editors in the 1980s. In 1983, Larry Wall introduced syntax highlighting while developing the vi editor for the Perl language. Today, virtually all modern IDEs and code editors include syntax highlighting as an indispensable part of programmers' daily workflow.
Popular syntax highlighting engines: Widely used libraries include Prism.js (known for being lightweight and extensible), Highlight.js (supporting 200+ languages), and Shiki (based on VS Code's engine for editor-consistent coloring). This tool is a lightweight pure-frontend implementation that delivers excellent highlighting without loading any external libraries.
This tool supports syntax highlighting for 20+ programming languages, including: JavaScript, HTML, CSS, Python, SQL, JSON, XML, Bash/Shell, PHP, Java, C, C++, Go, Rust, TypeScript, YAML, and Markdown. Each language has dedicated lexical rules that accurately identify keywords, strings, comments, numbers, and other tokens.
No. This tool runs entirely in your browser. All processing (including syntax analysis and style rendering) happens locally on your device. No data is ever sent to any server. You can even use this tool without an internet connection after the page has loaded.
Click the "Export HTML" button in the preview panel to download the highlighted code as a self-contained HTML file with inline CSS styles. You can embed it directly into web pages, blogs, or technical documentation without any external dependencies.
Yes. Find the "Show Line Numbers" toggle in the control panel. Turning it off removes line numbers from the preview, which is useful for taking screenshots or copying plain code content. The line number display state does not affect the exported HTML file.
Yes. The tool automatically detects the programming language based on code content (file extensions, common syntax patterns, etc.). The accuracy is high for most common languages, but complex mixed-language scenarios may require manual selection. You can always manually specify the language from the dropdown menu.
There is no strict limit on code length, but due to pure-frontend processing performance constraints, we recommend processing no more than 100,000 lines at once. For very large files, consider processing them in chunks.
The current version provides a unified dark theme color scheme. If you need custom colors, you can modify CSS variables via browser developer tools, or manually edit the CSS styles after exporting HTML.
The current version focuses on syntax highlighting and does not include code formatting. If you need to format your code, please use dedicated tools in our matrix such as "JSON Formatter," "HTML Formatter," or "CSS Formatter."
Type code to see highlighting...';
updateStats();
}
document.getElementById('btnHighlight').addEventListener('click', doHighlight);
document.getElementById('btnCopy').addEventListener('click', copyCode);
document.getElementById('btnExportHTML').addEventListener('click', exportHTML);
document.getElementById('btnClear').addEventListener('click', clearAll);
codeInput.addEventListener('input', () => {
updateStats();
doHighlight();
});
langSelect.addEventListener('change', doHighlight);
lineNumCheck.addEventListener('change', doHighlight);
doHighlight();