How can I formally validate the structure of an .epub file and check it for errors?

  • 1
    Note that a formal validation of the structure is no guarantee that the book works properly on various readers. A good additional step would be to try reading the book in software such as calibre, plus whatever hardware you own yourself.
    – user276
    Commented Dec 28, 2013 at 20:06

2 Answers 2


IDPF, the consortium that promotes the .epub standard, has released a tool named epubcheck.
It is available both via an online web-app here, or as a stand-alone program here.

There is also another tool called FlightCrew, available here; this is also integrated within Sigil, a full fledged epub editor (available here).

All these tools are free and cross-platform.


I have found eBookIt's online validator very good: http://www.ebookit.com/epub-validator3

[No longer exists at the specified location/URL]

  • 2
    Isn;'that just a packaging of the idpf validator?
    – mmmmmm
    Commented Jan 3, 2014 at 0:35

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