Transposon calling cards is a genomic assay for identifying transcription factor binding sites in both bulk and single cell experiments. Here, we describe the qBED format, an open, text-based standard for encoding and analyzing calling card data. In parallel, we introduce the qBED track on the WashU Epigenome Browser, a novel visualization that enables researchers to inspect calling card data in their genomic context. Finally, through examples, we demonstrate that qBED files can be used to visualize non-calling card datasets, such as Combined Annotation-Dependent Depletion scores and GWAS/eQTL hits, and thus may have broad utility to the genomics community.

Availability and implementation

The qBED track is available on the WashU Epigenome Browser (, beginning with version 46. Source code for the WashU Epigenome Browser with qBED support is available on GitHub ( and A complete definition of the qBED format is available as part of the WashU Epigenome Browser documentation ( We have also released a tutorial on how to upload qBED data to the browser (

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