Validate Your EPUBs

If you’re creating EPUBs and want to be sure they conform to standards expected by all EPUB reader software, you can use the EPUB Validator tool at www.threepress.org. Just upload your EPUB file and you’ll get a report.

Another option is EpubCheck, which can also detect errors in OCF container structure, OPF and OPS mark-up, and internal reference consistency. Get it at http://code.google.com/p/epubcheck/.