In addition to the bots others mentioned, there are web front-ends to provide scrollback. Convos [1a], TheLounge [2a], KiwiIRC+KiwiBNC [3]

I prefer to instead run irssi+otr in a GNU screen session from a random VM/VPS provider. Most others prefer tmux. I'm just stuck in the past I suppose for using GNU screen.

[1a] - https://github.com/convos-chat/convos/

[1b] - https://convos.chat/

[2a] - https://github.com/thelounge

[2b] - Demo: https://demo.thelounge.chat/#/connect

[3] - https://github.com/kiwiirc/kiwiirc