How do you know that you’ve produced an interoperable, functional, and accessible ebook? How do customers know? Or libraries? Or Book distributors? Validation is the cornerstone of the epub publishing process and there is one system on which nearly all epub relies – epubcheck. However, as our standards evolve, our validation has not and epubs meeting the most recent specification requirements aren’t always declared valid by the system of record. In order to make better epubs, we need a better epubcheck.
What is epubcheck?
Epubcheck is the opensource validation tool for the EPUB format. Unlike many validation tools, epubcheck is seen as a gatekeeper for the entire publishing industry. Because many retailers will not accept a file that has not passed epubcheck, it has become the (loveable) bridge troll that determines if a publisher or author’s product is ready to be released for sale. It can detect many types of errors in EPUB: OCF container structure, OPF and OPS markup, and internal reference consistency are all checked and can be run as a standalone command-line tool or used as a Java library. As the tool upon which the whole ebook industry relies to validate ebooks, epubcheck 4.0.2 is anxiously awaiting an upgrade.
How did epubcheck evolve?
Epubcheck was built and has been maintained by volunteer developers. Contributors have come from different organizations and individuals with interests in validating epub. But the last few years have been a developmental dry spell. In 2017 and 2018, I gathered a task force of people involved in epubcheck, EPUB, and testing at W3C to brainstorm about solutions for maintenance and developing the next set of tests to support the current version of the EPUB spec. After many discussions, we concluded that we need a technical lead to determine the technical direction of epubcheck. The result of a volunteer-led effort can be a messy set of tests. We need to clean up the repo, establish tests for EPUB 3.2, and refactor the existing tests so that they are easier to maintain in the long term.
What’s Next for epubcheck?
Eighty-five open issues await review and resolution in the epubcheck repository and as the EPUB Community Group sprints toward the finish line of EPUB 3.2, that list will grow. As a result, The Publishing Business Group of the W3C has put out a request for proposals for epubcheck Development and Maintenance at epubcheck RFP.
Please contact me or the Publishing Steering Committee with questions.