Purpose of this package is it to plan, monitor and evaluate oncological phase II studies. In general this kind of studies are single-arm trials with planned interim analysis and binary endpoint. To meet the resulting requirements, the package provides functions to calculate and evaluate 'Simon's two-stage designs' and 'so-called' 'subset designs'. If you are unfamiliar with this package a good starting point is to take a closer look at the functions getSolutions() and getSolutionsSub1().The web-based tool (< https://imbi.shinyapps.io/phaseII-app/>) extends the functionality of our R package by means of a proper dealing with over- and underrunning. The R function binom.test of the 'stats' R package and the package 'binom' might be helpful to assess the performance of the corresponding one-stage design as a reference.