EPUB Checker
When exporting documents to EPUB format, it’s important to check them for errors — especially if you edited it after exporting. One tool that helps is EpubCheck, which can detect many types of errors in EPUB. OCF container structure, OPF and OPS mark-up, and internal reference consistency are also checked.
Get it at http://code.google.com/p/epubcheck/ or https://github.com/IDPF/epubcheck.
Jay Nelson is the editorial director of PlanetQuark.com, and the editor and publisher of Design Tools Monthly. He’s also the author of the QuarkXPress 8 and QuarkXPress 7 training titles at Lynda.com, as well as the training videos Quark includes in the box with QuarkXPress 7 . In addition, Jay writes regularly for Macworld and Photoshop User magazines and speaks at industry events.