D21 File - opening and understanding
Did your computer fail to open a D21 file? We explain what they are used for and recommend software that we know can open or otherwise handle your .D21 files.
What is a D21 file?
The D21 file extension indicates to your device which app can open the file. However, different programs may use the D21 file type for different types of data.
While we do not yet describe the D21 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 D21 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!
How to open D21 files
You will need a program compatible with the specific file you are trying to open, as different programs may use files with file extension D21 for different purposes.
While we have not verified the apps ourselves yet, our users have suggested 1 different D21 openers which you will find listed below.
Various viewers for this file format
These apps are known to open certain types of D21 files. Remember, different programs may use D21 files for different purposes, so you may need to try out a few of them to be able to open your specific file.