The MIT Categories Seminar is an informal teaching seminar in category theory and its applications, with the occasional research talk. This spring they are meeting online each Thursday, 12 noon to 1pm Eastern Time.
Here are some forthcoming talks:
March 26: David Jaz Myers (Johns Hopkins University) — Homotopy type theory for doing category theory.
April 2: Todd Trimble (Western Connecticut State University) — Geometry of regular relational calculus.
April 9: John Baez (UC Riverside) — Structured cospans and Petri nets.
April 16: Joachim Kock (Universitat Autònoma de Barcelona) — to be announced.
April 23: Joe Moeller (UC Riverside) — to be announced.
Videos of many older talks are available here.