Agar is a gelatin-like product made primarily from the red algae Gelidium and Gracilaria (division Rhodophyta). It is commonly used in Asian cuisines and as a flavorless vegan substitute for gelatin. Agar is a gelatin-like product made primarily from the red algae Gelidium and Gracilaria (division Rhodophyta). It is commonly used in Asian cuisines and as a flavorless vegan substitute for gelatin.