<jats:p>The 27th Bioinformatics Open Source Conference, BOSC 2026, took place July 14-15 as part of Intelligent Systems for Molecular Biology (ISMB) 2026, in Washington, DC, USA (with a virtual participation option). About 2100 people attended ISMB 2026 (1800 in person), with 10 or more parallel sessions to choose from every day. We estimate that over 200 people participated in BOSC.</jats:p>