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Test the epub

There are two parts to testing your epub. First, check that it is valid. For this, use epubcheck. (Most distributors will only accept valid epub files.) A related tool called epubpreflight tests for a few other problems.

Second, “field test” the epub in a variety of ereading systems.


Epubcheck is a tool developed largely by Adobe to check whether epubs are valid. Get it here.

(Epubpreflight is also available there. It works in a similar way but tests for things taht won’t invalidate the epub, but will make it work inconsistently across devices.)

The easiest way to use epubcheck is to use the Threepress web-based validator. It’s slower but easier (for most people) than using epubcheck from the command line.

Using epubcheck from the command line

First, see the instructions here.

To run the tool you need Java (1.5 or above) installed on your computer.

To run epubcheck (version 1.0.5) from the command line:

  • Create a folder on your local machine for epubcheck. It’s often easiest if this is in your root directory (e.g. c:/epubcheck).
  • Copy the epubcheck files (unzipped) into that directory.
  • Copy the epub you want to check into that directory.
  • Open a command prompt (in Windows XP, click Start>Run, type cmd, and hit Enter).
  • In the command prompt, go to your new directory (e.g. c:/epubcheck). To move down a directly, type cd.. and to move into a directory, type cd/directoryname (e.g. cd\epubcheck).
  • When you’re in the epubcheck folder, type
java -jar epubcheck-1.0.5.jar file.epub

where 1.0.5 is the release number of your copy of epubcheck, and file.epub is the file name of your epub. Hit enter and you’ll get your test results.

“Field” testing

Always, always test on a few different devices, and scroll through the whole book for a visual check. We recommend that you test on:

These tests should include a device with a small screen (less than, say, 5” diagonal; this can detect various formatting problems) and one with a large screen (above, say, 19”; this can detect low-res covers and missing page breaks).

They will usually also include a device with an Adobe engine (e.g. Adobe Digital Editions or a device based on the Adobe Reader Mobile SDK, such as Sony Readers and B&N Nook), and a device with a WebKit engine (e.g. Ibis Reader, iBooks on the iPad). (This distinction is explained in this presentation by Liza Daly.)

Arthur Attwell last updated 17 February 2010
This information is more than two years old, and may no longer be accurate.