EPUB validator
EPUBCheck is a tool to validate the conformance of EPUB publications against the EPUB specifications. EPUBCheck can be run as a standalone command-line tool or used as a Java library. EPUBCheck is open source software, maintained by the DAISY Consortium on behalf of the W3C.
Homepage: https://github.com/w3c/epubcheck
Maintainer: Anthony J. Bentley <anthony@anjbe.name>