Convert HTM to XHTML

Understanding HTM and XHTML file formats

HTM is a file extension for HTML (HyperText Markup Language) documents, commonly used for web pages. The .htm extension is functionally identical to .html, and both are used to structure content for web browsers. XHTML (Extensible HyperText Markup Language) is a stricter, XML-based version of HTML. XHTML files must follow XML syntax rules, making them more robust for data interchange and web development.

Why convert HTM to XHTML?

Converting HTM to XHTML ensures your web pages are compliant with XML standards, which can improve compatibility with modern browsers and devices. XHTML is also preferred for projects that require strict markup validation or integration with XML-based technologies.

How to convert HTM to XHTML

To convert an HTM file to XHTML, you need to ensure the markup is well-formed and follows XML rules. This includes properly closed tags, lowercase tag names, and quoted attribute values.

Best software and tools for HTM to XHTML conversion

• Notepad++ with the XML Tools plugin: Open your HTM file, use Plugins → XML Tools → Pretty Print (XML only) to format, then manually adjust the markup to meet XHTML standards. Save the file with a .xhtml extension.
• HTML Tidy: A command-line tool that can automatically convert HTML to XHTML. Use the command tidy -asxhtml input.htm -o output.xhtml to perform the conversion.
• Online converters: Websites like FreeFormatter allow you to paste your HTM code and convert it to XHTML instantly.

Step-by-step conversion using HTML Tidy

1. Download and install HTML Tidy from the official website.
2. Open a command prompt or terminal window.
3. Run the command: tidy -asxhtml yourfile.htm -o yourfile.xhtml
4. Review the output file for any warnings or errors and make manual corrections if needed.

Tips for successful conversion

• Ensure all tags are properly closed (e.g., <br /> instead of <br>).
• Use lowercase for all tag and attribute names.
• Quote all attribute values.
• Validate your XHTML file using the W3C Markup Validation Service.