Their iOS version is quite expensive if I recall correctly. It also isn't quite up-to-date in its design. Neither are any of the Anki apps, in my opinion. Anki

Their iOS version is quite expensive if I recall correctly. It also isn't quite up-to-date in its design. Neither are any of the Anki apps, in my opinion. Anki does have a huge advantage from its excellent spacing algorithm. The prototype I have working so far uses the Leitner system, which is very basic, but an advantage of keeping all the data on the web is the huge potential for A/B testing to figure out the actual best spacing algorithm. Lastly, I'm not too interested in generating revenue from this project. I don't even have any ideas for monetizing it. This is mainly to scratch my own itch. If I can make enough to cover the cost of running the project (which is currently zero; it's being hosted on a free heroku dyno), I'll be happy.