Files can be received over the DCC protocol with resume support.
Configure the notifications you want to receive for each network by channel, sender or message. Create as many notification rule sets as required so you don't miss anything important.
Authenticate to configured servers with SASL PLAIN, SASL EXTERNAL or SASL SCRAM-SHA-256, or just using plain old NickServ. CoreIRC supports a wide range of the IRCv3 spec.
Inline URL previews, fun scripts like Now Playing and System Information, command and nickname autocomplete, IRC / mIRC colour support, and there's still more!