The Cancer Research Institute (CRI) iAtlas is an interactive web platform and a set of analytic tools for studying interactions between tumors and the immune microenvironment. These tools allow researchers to explore associations between a variety of genomic characterizations of immune response, clinical phenotypes, germline genetics, and response to immunotherapy. Immune checkpoint inhibitor analysis modules allow for interactive exploration of the relationship between possible biomarkers of immune response and the outcome of response to checkpoint blockade, by direct comparison and using multivariable statistical models. Underlying these modules is a harmonization of primary sequencing data from 12 immuno-oncology trials with genomics data and matched clinical data available in the public domain. iAtlas also allows researchers to identify how tumor-intrinsic alterations, including mutations, copy-number alterations, and neoantigens relate to the immune microenvironment as evidenced in cancer genomic studies.