Thank you for open sourcing Forum Fiend, which was used as a working reference model to develop Forum Friends - a multi-platform forum discussion app. It was necessary to completely rewrite Forum Friends from the ground up to support Android, IOS and desktop browsers.
Regarding legal issues with the use of the Tapatalk api, decades of case law support the fact that an api is not copyrightable. In addition there are a number of open source implementations of the Tapatalk api available on git for different forum systems.
In developing Forum Friends I have accumulated a good amount of experience in working with the Tapatalk api as well as Forum Fiend. I have encountered many of the issues brought up in this thread, for instance, it was mentioned that it takes a long time to load xda-developer.com into Forum Fiend, or it appears that the app hangs. This is due in part to the Tapatalk api sending the entire list of forums on xda-developer.com to the app encoded as xml-rpc values, a situation that generates several megabytes of data to download and process. Forum Fiend then goes through several stages in processing this data where each stage stores a copy resulting in excessive memory consumption as well as requiring a lot of processing time. The Tapatalk app is not much better at dealing with this scenario as it also downloads and processes the entire list of forums.
Another issue is maintaining persistent login sessions. Most CDNs do not handle preserving session cookies very well and a logged in session only lasts for a few api requests at best. But it is a rather cumbersome problem to deal with in Forum Fiend with the way asynchronous requests are handled.
A separate thread has been created for Forum Friends. Forum Friends is available now on Google Play, search for "Forum Friends".
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