I would like to present my attempt to make a Codeforces API wrapper for Java. As it can be clearly seen while browsing GitHub, there're some takes on making it but none of them is finished (believe me, I've checked). Many amazing things can be done via Codeforces API, such as this app, this site, or this app.
And there are a lot of other projects that can be done via write methods API that are currently done by page parsing, such as all sorts of CLIs for Codeforces. Hope that in some time in the future they would be added to the official API, so the development of such applications would become much easier.
Feel free to point at any issues that you can find in the project. Currently, I'm planning to add some automated codestyle and other checks. Also, feel free to contribute to the project in any way you like.
With best regards, Pavel.