Xu, W.; Wu, Y.-H.

1. Historical biogeography increasingly looks beyond one clade at a time, pooling range-evolution and speciation events from lineages that share a region to ask whether the same geological and climatic events shaped them together. Despite the momentum behind this cross-clade synthesis, it still has no dedicated software. 2. We present BioGeoSyn, an open-source graphical application (with an equivalent scripting interface) that makes a complete, reproducible BioGeoBEARS analysis point-and-click: guided data upload and validation, model fitting and comparison, biogeographic stochastic mapping (BSM), and standardized tables, publication figures and a report. 3. Its one novel capability is cross-clade synthesis. Once every clade's events carry the same seven process labels and sit on a common time axis, BioGeoSyn integrates event rates through time, overall and region-resolved, across independently analysed clades, each carrying a 95% interval propagated from the stochastic maps, to reveal shared biogeographic pulses. 4. BioGeoSyn lowers the barrier to reproducible historical biogeography for non-programmers and provides a ready-to-use route to multi-clade biogeographic-event synthesis.