When comparing Kiwi IRC vs IRSSI, the Slant community recommends IRSSI for most people. In the question“What are the best IRC clients for Windows?” IRSSI is ranked 8th while Kiwi IRC is ranked 17th. The most important reason people chose IRSSI is:
Screen multiplexing and remote connection options with screen or tmux.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Beautiful interface
Kiwi's default interface is aesthetically modern, while keeping a classic two-column layout with chat window on the left and nicklist on the right. Unlike many other interfaces, a considerable amount of effort has been spent on making it easy on the eyes.
The interface offers common customization options including time format changes, choice of system messages and choice of laying out channels in a tabbed or list manner.
Pro Free and open source
Kiwi IRC web client is available for free licensed under GPL with source available on GitHub.
Pro Embeddable
Code can be generated that allows embedding the IRC client within a website.
Pro Available in multiple languages
Kiwi's front-end is available in more than 20 languages including Polish, Romanian and Russian.
Pro Terminal-based
Screen multiplexing and remote connection options with screen or tmux.
Pro Themes
Allows the modification of IRSSI's look and feel.
Pro Free and open-source
Pro Quick and easy setup
3 or 4 commands and you're ready to chat with all your old friends.
Pro Perl scripting
Allows the user to create and use perl scripts to perform actions.
Pro Command line outputs can be sent to a channel or message
/exec -o figlet "Slant.co"
Pro Easy logging
Pro Persistent connection
Pro Has a plugin for encrypted communications
Cons
Con Notifications don't time out
Notifications pop-ups have to be closed manually each time, they don't disappear on their own after a set amount of time.
Con Requires additional install, i.e. 'must have this' to run
Con No GUI
Actually a plus for some, lower memory overhead.
Con Gives little direction upfront
Actually, Irssi.org has it's own GREAT documentation for new irssi users. Inline /help options are pretty well documented.