Persephone is a state-of-the-art industrial-scale genome browser, capable of rapidly showing large data sets. It visualizes genomic sequences with various tracks, genetic maps, QTLs, SNPs, synteny, etc. The company's latest development is a web version of Persephone that runs in a browser. The use of advanced technologies allows it to handle massive amounts of data, traditionally challenging for web browsers. Besides the high performance, its main characteristic feature is the ability to align several maps on one screen and compare genomic sequences and genetic maps. The fast rendering is not just making it pleasant to use, it also makes it possible to browse very large data sets in real time. Persephone handles volumes of data typical for corporate repositories: hundreds of millions of maps, billions of SNPs, etc. The web version, ready to be used by the scientific community, is available for free at the company's genomic portal https://web.persephonesoft.com.