IRC: I'm on the EFnet irc network. Since they do not support nick (name) ownership, I could 'loose' my nick to someone else at any time. While this is not a problem right now, it was a problem once in the distant past, and could be a problem any time in the future as well. So, if you choose to contact me via EFnet, you might want to make sure it is really me you're talking to. I'm also on Libera IRC, and my nick is registered there. I may or may not still be on FreeNode.
Skype: You should be able to send me a message on Skype, without adding me as a friend. Skype is my preferred method of communication, now that they've fixed it for Linux.
WeChat/Weixin: Yes, I use WeChat, because of my close ties with China.
EMail: Use the following form, to send me an email. All 3 fields must have something in them, and you need to check the box that indicates that you are not a robot, before it will send your message. If you want a response from me, then make sure you use a proper email address that I can contact you at. If you want to send your message anonymously, then don't use a proper email address.