Abstract Motivation: Nonlinear dose–response models are primary tools for estimating the potency [e.g. half-maximum inhibitory concentration (IC) known as IC50] of anti-cancer drugs. We present drexplorer software, which enables biologists to evaluate replicate reproducibility, detect outlier data points, fit different models, select the best model, estimate IC values at different percentiles and assess drug–drug interactions. drexplorer serves as a computation engine within the R environment and a graphical interface for users who do not have programming backgrounds. Availability and implementation: The drexplorer R package is freely available from GitHub at https://github.com/nickytong/drexplorer. A graphical user interface is shipped with the package. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online.