The app does sample sizes for Binary, Normal and Survival data (number of events for survival). For different trial objectives (Superiority, Non-inferiority, Equivalence, Precision and Bioequivalence) and study designs (Cross-over and Bioequivalence)
If you access the app through an Android device on accessing the website you will be asked if you wished to install the app. By agreeing SampSize will be installed as an app on your device and could be run without being on a network.
If you do not get the query then while on the website if you click 'Add to Home Screen' the app will be on your phone and you will not need to be on a network
For an IOS device, you will not get the download prompt. Select 'Add to Home Screen' to open the 'Add to Home' dialog box. Again SampSize will look and work like an app on your device and you do not need to have access to a network to run it.
You do not need to have on your device as SampSize will work from the website.