Just about everything works through the Beeminder API.
Note that these are in no way official, tested, or endorsed, though some of them have been incorporated into the Beeminder GitHub for safekeeping. I found them on the web, you could too. With a bit of luck they're still in active use and their authors are here on the forum…
Here, let me search GitHub for you.
Libraries wrapping the Beeminder API
This list is wildly incomplete, please add any libraries that you rely on, as well as good examples for others to follow. This post is a wiki. Thanks!