In this workshop we will explore the capabilities of the validated open-source R package 'rpact', which is available on CRAN and GitHub. rpact is a comprehensive validated, open source, free-of-charge R software package for clinical trial planning, design simulation, and data analysis. rpact is under continuous full-time development since 2017, and comprehensive documentation is available at www.rpact.org. We will provide an introduction to the package and illustrate the usage by several examples. The focus of the package is on group sequential and adaptive designs with p-value combination tests, but also fixed sample designs can be considered. The software can specifically be used to assess design characteristics of popular group sequential designs. However, going beyond those, adaptive designs are a strength of rpact: Adaptive multi-armed and population enrichment designs that are based on closed combination tests can be assessed by simulation. The application of the designs for simulation, real data, and estimation is possible for continuous, binary, survival, and count data. Furthermore, we introduce 'RPACT Cloud', a user-friendly platform designed to simplify and enhance the process of clinical trial design and simulations for researchers and practitioners. A free version of RPACT Cloud is available at https://cloud.rpact.com/ and workshop participants will be able to try out the software themselves following the workshop.