You can simply rename extension to HTM to HTM, however most - if not all - programs that work with HTML format should be able to work with both extension so there should be no need for this and same goes for conversion - not needed.
Convert HTML Hypertext Markup Language web page to HyperText Markup Language web page.
We found 27 software records in the database related to .htm to .html file format conversion.
Microsoft Windows software - convert htm to html on Windows
A web publishing and website mangement tool from Adobe
Convert from htm file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned htm to html. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A powerful text and source codes editing tool
A free e-book library management application
Program for ePUB conversions
A dedicated XML editor
Adobe' proprietary rapid application development platform
IDE used to create ColdFusion applications
Note organiser software
Apple macOS / Mac OS X software - convert htm to html on OS X
Mac version ColdFusion development environment
A free open source ebook creator, converter and viewer
A Mac version of the popular word processing application
A text and source code editing software for Mac
HTML and PHP editor
A sophisticated Mac source code editor for programmers
Web editing tool for Mac
A popular spreadsheet application from the Microsoft Office suite
Linux/Unix software - convert htm to html on Linux
Default file manager installed in KDE desktop
A sophisticated Linux source code editor for programmers
Multiplatform software - convert htm to html on any platform
Integrated development tool and source code editor for Windows, Mac and Linux