There are two main reasons why textbooks are evaluated; the first of which is associated to the task of textbook selection (predictive evaluation) and the second to the need to evaluate it while in use (retrospective evaluation) so that teachers can implement adaptation procedures later. Predictive evaluation is almost nonexistent in most developing countries as textbooks are usually provided free or through a textbook loan scheme. There is however hope for getting teachers involved in while-use/post use or retrospective evaluation of textbooks as they not only help teachers with adaptation but help teachers in their overall professional development. Since textbooks are an essential part of the teacher's professional life any form of out-of-class work that involves the teacher's own knowledge building can become an integral part of the teacher's professional development. This article introduces software for textbook evaluation, Retrotext-E 1.0, which among other functions, uses text files (txt) of the digitized pages of the textbook to analyze vocabulary and distribution patterns in the book. This software tool supports retrospective evaluation of textbooks and can be a useful tool for teachers not only evaluating textbooks but researching them.