A spline font format, such as TrueType or OpenType, that is accepted by the W3C for web development. The web open format is essentially a zlib compressed font file format that is small enough to be embedded in a web page and downloaded as necessary for viewing that web page.

Although there is not much browser support in the mainstream browsers for this format, the W3C expects to make this format a requirement for compliance and expect to see complete support for it from all web browsers in the near future.