The Diffiety Institute was established in 1995 from the research seminar Algebra and geometry of differential equations. The Institute was closed in 2005, although the website is still maintained. The main activity of the group was scientific research in algebra and geometry of differential equations and cohomological physics and the group was responsible for organising seminars and conferences in this area. They also provide a preprint archive, with papers avaiable for downloading in PostScript, DVI or PDF format, and software products.