YeenChat is a retro instant messaging server that attempts to preserve the early internet social experience. The server is entirely compatible with old versions of AIM (AOL Instant Messenger) and ICQ, letting you communicate with your friends through the same software that was prevalent in the 90s and early 2000s..
To connect, you will need an AIM-compatible client. I personally use the original AIM 5.9 client, but clients such as Phoenix IM or Miranda NG work just fine.
If you are using the classic AIM 5.9 executable on modern Windows, you may need to adjust the executable's compatibility settings. Right-click the executable, go to Properties > Compatibility, and check the box to "Run this program in compatibility mode for: Windows XP (Service Pack 3)".
In your client's login or connection settings screen, look for the Host or Server field. Replace the default AOL server address with:
aim.yeenchat.org
Ensure the port is set to 5190. Make sure any options for "Secure Connection (SSL/TLS)" are unchecked, as the chat server uses a raw TCP connection.