First we need to support only protocols where an open source /free client can be written. Then I am free to use it (the best I can find) and other people can us

First we need to support only protocols where an open source /free client can be written. Then I am free to use it (the best I can find) and other people can use any one they choose. I avoid using anything that requires a proprietary client. If I really have to, I'll use a web client and not be online most of the time.