The idm file extension has three different file types (mostly seen as the ulead photo express messages file format) and can be opened with three distinctive software programs. However, different programs may use the idm file type for different types of data. Idm Extension File : How To Add Idm Extension In Chrome Manually Sociallypro - Whereafter downloading some part of the file, the download fails or shows any different similar also, the extension should be installed automatically during the idm installation.