Character Set Viewer
Online application that presents all glyphs from a TTF or OTF font, including their OpenType alternatives (GSUB and GPOS).
Glyphs in the fonts can be sorted by GID or Unicode, and presentation can be customised (grid size, font colour, font sizes, glyph descriptions, etc).
Fonts are hosted on a network of secure servers making the service extra fast and reliable, but the interface is fully integrated to client's website. Because browsers have limits on how many simultaneous requests they can make to individual servers, hosting fonts on third-party servers will utilise more connections, loading files much faster than if they were hosted on the same server.