Opening HTM files

Have a problem opening a .HTM file? We collect information about file formats and can explain what HTM files are. Additionally we recommend software suitable for opening or converting such files.

What is the .HTM file type?

The .htm extension represents the Hypertext Markup Language (HTML) file type. HTM files are plaintext files containing user text with HTML-specific markup tags inserted in-between. An .htm file is the source code of a web page displayed in a web browser. Tags define the structure of the document and contain instructions for the browser how to display the web page.

HTM files are universally plaintext, human-readable, cross-platform, and editable with any text editor, many of which allow HTML syntax highlighting. Being plaintext, HTM files are ASCII-, ANSI- or Unicode-encoded.

The .htm extension serves the same purpose as the .html, both being alternative ways to denote the same HTML file type. Historically, the .htm notation evolved from the DOS/Win 3.x era with its 3-digit extension length limit.

Many web servers treat .htm files the same way as .html files, serving them with the same 'text/html' MIME type by default. However, there may be extension naming requirements in place on a web server so that either .htm or .html is preferred.

Software to open or convert HTM files

You can open HTM files with the following programs: 

Popular formats