A few people have replied, saying how to get chat history with IRC, but as far as I can tell, none of them work like Slack. With Slack, you can see history from before the first time you connect. It looks like none of the IRC solutions enable that; the IRC protocol doesn't make it possible, without the server (or a channel member) keeping logs.
(I haven't used either very much, so please correct me if I'm wrong.)
IRCCloud can, they're a client too :) I highly recommend them if you are serious about IRC.
But yes you're right, nothing in the IRC protocol for it. There is something in IRCv3 to provide chat history but I don't know if it's even in the current version of the spec.
Like I was saying, IRCv3 has support for replaying the channel's history, as long as it's stored serverside. But I don't know if anything actually implements it, even IRCCloud which is v3-compatible.
At the moment if you join a channel you can't read its backlog, no. They could implement it though if they used logs from their users... kinda wish they would. But hey.
> At the moment if you join a channel you can't read its backlog, no.
Then I'm not entirely sure what you were referring to, when you said "IRCCloud can". Backlog from before you joined the channel is the specific feature that I was saying couldn't be done.
It's interesting to know that IRCv3 does have that support, so I was wrong about it not being possible. But if nothing implements it, it's not very helpful.
(I haven't used either very much, so please correct me if I'm wrong.)