Group Sequential Design for Historical Control Trial with Survival Outcome R package HCTDesign version 0.7.4 It provides functions to design historical controlled trials with survival outcome by group sequential method. The options for interim look boundaries are efficacy only, efficacy & futility or futility only. It also provides the function to monitor the trial for any unplanned look. The package is based on Jianrong Wu, Xiaoping Xiong (2016) <doi:10.1002/pst.1756> and Jianrong Wu, Yimei Li (2020) <doi:10.1080/10543406.2019.1684305>. Software Imports: Rdpack, diversitree, mvtnorm, flexsurv, stats, survival, crayon Tushar Patni <tushar.patni006@gmail.com> Comprehensive R Archive Network (CRAN) Tushar Patni [aut, cre], Yimei Li [aut], Jianrong Wu [aut] GPL-3 2025-10-20 application/tgz https://CRAN.R-project.org/package=HCTDesign doi:10.32614/CRAN.package.HCTDesign