Fontmatrix is a font management application for Linux, Mac and Windows, concieved by Pierre Marchand in 2007. It helps keeping your font collection in order, allowing you to enable and disable availability of fonts and font families in your system. This is a quite helpful tool for designers who tend to have huge collections of typefaces. Searching for the right font in Fontmatrix is easy thanks to advanced support for Panose and user defined filters, as well as tags. Fontmatrix is also useful for type designers and enthusiasts, because it simplifies testing of OpenType features and allows comparing fonts glyph by glyph which is extremely useful for learning type design. There is an extremely low-traffic mailing list available: https://mail.gna.org/listinfo/undertype-users/