EPUB 3 Best Practices

Chapter 4. Font Embedding and Licensing

Adam Witwer

Director of Publishing Technology, O’Reilly Media

When you “embed” a font within an EPUB file, you include single or multiple font files in the EPUB package. You must then include references to that font within the CSS and the OPF manifest of the EPUB so that the font is rendered across reading systems. Sounds simple enough, right? From a technical perspective, embedding fonts is simple, and the EPUB 3 specification leaves little room for ambiguity on this topic. It is a straightforward enough process that a technical overview can be summarized succinctly in a single blog post.^[1]

While embedding fonts in an EPUB file is simple enough, how reading systems support embedding has been and remains spotty and inconsistent, often frustratingly so. Also, while embedding fonts is trivial, adding the required obfuscation—required by most commercial font foundries—is much less so. Also, licensing for embedding in general can be an administrative and technical nightmare.

This chapter does not argue for or against embedding fonts, or perhaps more accurately, it argues for both. In doing so, the chapter aims to give you the information that you need to decide for yourself what the “best practice” is around font embedding, which will be influenced by a number of factors, including—perhaps most importantly—the kind of content that you publish. There is not one reason why you might want to embed a font in an EPUB—your reasons may range from capturing ...