Back when I was an undergrad student, I used Skype frequently to text chat with friends. We didn’t make much use of audio or video calling. The official skype client had a tendency to bog down my computer, so I set out to create a lightweight text-only skype client.
I used Skype’s public C++ SDK, Skypekit, to build a very stripped down skype client. It was able to send messages, receive messages, and view contact statuses, but not much else. But importantly is used way less memory than the official client.
Like most things I wrote while I was a student, the code was a mess and I never released it publicly beyond showing it to a few friends.