Summary: We developed hdnom, an R package for survival modeling with high-dimensional data. The package is the first free and open-source software package that streamlines the workflow of penalized Cox model building, validation, calibration, comparison, and nomogram visualization, with nine types of penalized Cox regression methods fully supported. A web application and an online prediction tool maker are offered to enhance interac- tivity and flexibility in high-dimensional survival analysis. Availability: The hdnom R package is available from CRAN: https://cran.r-project.org/package=hdnom under GPL. The hdnom web application can be accessed at http://hdnom.io. The web application maker is available from http://hdnom.org/appmaker. The hdnom project website: http://hdnom.org.