Heatmapper2: web-enabled heat mapping made easy.

First released in 2016, Heatmapper provided the first comprehensive, web-based platform for easily visualizing and manipulating heat maps for a wide range of applications in biology, epidemiology, ecology, and many other areas of science and social science. However, as Heatmapper's popularity grew, limitations in its performance and functionality became more apparent, necessitating the development of a new version: Heatmapper2 (https://heatmapper2.ca/). Heatmapper2 represents a substantial upgrade to the original Heatmapper web server, with much of the code being completely rewritten to improve performance, enhance capabilities and integrate new web technologies. Among the key changes are the conversion of the back-end code from R to Python (for better processing speed), the migration away from R Shiny to Shiny Python, and the use of WebAssembly. WebAssembly enables high performance, graphically intense applications to be run client-side in a web browser. Moving computationally intense calculations away from a central server and on to client computers eliminates server congestion and significantly improves performance. In addition to its significantly improved performance, Heatmapper2 now supports a wider range of heat mapping options including: time-series or animated heat maps (for geospatial applications), 3D heat maps (for mapping data on organisms or body parts); protein structure heat maps (for mapping molecular dynamic processes), molecular spatial heat maps (for spatial omics applications), and spectrometric heat maps (for mass spectrometry applications). Heatmapper2's redesigned interface also supports much more extensive customization, more easily editable tables, and more efficient handling of large datasets. These enhancements should make Heatmapper2 much more appealing for a wider range of researchers and research applications.