Sample Size Calculator for Survival Endpoint Clinical Trials // An interactive 'shiny' application for sample size and power calculation under general conditions for clinical trials with survival endpoints. Implements the weighted log-rank method of Lu (2021) doi:10.1002/pst.2069 via the 'lrstat' package, supporting non-proportional hazards, delayed treatment effects, unequal allocation and dropout, as well as the classic method of Freedman (1982) doi:10.1002/sim.4780010204 via the 'powerSurvEpi' package. Results are presented interactively with survival curves and event-prediction timelines.