The use of artificial intelligence in foreign language teaching, and particularly in teaching writing, is still under investigation for its potential positive impact and potential benefits. So far, the focus was on controversial uses, due to the challenges for the teachers. However, when used just for learning purposes, it can be a facilitating tool for the students. The key now is to understand its effects, challenges, and opportunities, to establish a framework for its use, and to make teachers aware of its potential. To this end, in this article we take a functional and utilitarian approach by identifying the characteristics and capacities of currently available sites. A description of the different sites is given along with their advantages and disadvantages. Since only a few fundamental works have been published on the subject, we propose a taxonomy with examples, evaluate its benefits and drawbacks and suggests potential applications for teaching and research.