How to open 21M files

Did your computer fail to open a 21M file? We explain what 21M files are and recommend software that we know can open or convert your 21M files.

What is a 21M file?

The 21M file extension indicates to your device which app can open the file. However, different programs may use the 21M file type for different types of data.

While we do not yet describe the 21M file format and its common uses, we do know which programs are known to open these files, as we receive dozens of suggestions from users like yourself every day about specific file types and which programs they use to open them.

We are continually working on adding more file type descriptions to the site, so if you have information about 21M files that you think will help others, please use the Update Info link below to submit it to us - we'd love to hear from you!

Generic 21M

These apps are known to open certain types of 21M files. Since many different programs may use 21M files for different purposes, you may need to try a few of the apps to open your specific 21M file.

CNC-ManagerCNC-ManagerUser submitted

Try a universal file viewer

Try a universal file viewer like Free File Viewer. It can open over 200 different types of files - and most likely yours too. Download Free File Viewer here.

We have not verified any programs that we know for certain can work with 21M-files on Mac. If you know one, please use the Suggest link below and tell us about it!
We have not verified any online services that we know for certain can work with 21M-files. If you know one, please use the Suggest link below and tell us about it!