AbstractSummaryProteinPaint BAM track (ppBAM) is designed to assist variant review for cancer research and clinical genomics. With performant server-side computing and rendering, ppBAM supports on-the-fly variant genotyping of thousands of reads using Smith–Waterman alignment. To better visualize support for complex variants, reads are realigned against the mutated reference sequence using ClustalO. ppBAM also supports the BAM slicing API of the NCI Genomic Data Commons (GDC) portal, letting researchers conveniently examine genomic details of vast amounts of cancer sequencing data and reinterpret variant calls.Availability and implementationBAM track examples, tutorial, and GDC file access links are available athttps://proteinpaint.stjude.org/bam/. Source code is available athttps://github.com/stjude/proteinpaint.