§ What is EPUBCheck?

EPUBCheck is the official conformance checker for EPUB publications. This short statement includes a lot of information already:

EPUBCheck is distributed as a command line program. It is also available as a Java software library, to be integrated as a component in larger systems.

§ Who is it for?

EPUBCheck is made for both content creators and content distributors. In fact, most of the digital publishing actors rely on EPUBCheck as a critical step in their workflows.

Using the official distribution of EPUBCheck will require you to be familiar with running programs in a command-line shell. But if you prefer to use a graphical user interface, it is absolutely fine! Good people created third-party apps and tools which can provide a friendlier user experience.

§ Why check your EPUBs?

EPUBCheck can detect mistakes or defects in EPUB publications. These flaws may cause interoperability issues and degrade the reading experience.

Content distributors will typically use EPUBCheck to decide if digital publications can be accepted in their catalogs. Most retailers will not accept an EPUB file unless it successfully passes EPUBCheck scrutiny. Content producers can use EPUBCheck to catch unintentional mistakes early on, so they can fix them.

§ What can it detect?

EPUBCheck will scan technical aspects of your EPUB, including:

But EPUBCheck cannot play an editorial role. It will not detect typos, mispellings, off-topic images, etc.