The Herbario Nacional (MEXU by its acronym in the Index Herbariorum), under the custody of the Instituto de Biología of the Universidad Nacional Autónoma de México (UNAM), holds ca. 1.6 million specimens in six collections, namely Algae, Bryophytes, Fungi, Historical Collection, Lichens, and Vascular Plants (the latter including subcollections Fruits and Seeds, Types, and Xylotheque). Nearly 1.3 million specimens are available online, in most cases including a high-resolution digital image, in our web platform IBdata 3 (www.ibdata.ib.unam.mx) and also through UNAM´s open data portal (https://datosabiertos.unam.mx/).