IRCCloud is web-based persistent IRC.
Ranked in these QuestionsQuestion Ranking
Pro Can stay connected while user is absent
IRCCloud offers an option to keep idling in a channel even when the user is not connected. This way no conversations or mentions will be missed while away.
Pro Inline media
IRCCloud has the ability to embed pictures, youtube videos, vines, etc straight within the chat window.
Pro Drag and drop filesharing
Files can be shared simply by dragging and dropping them into a channel. They will be hosted on IRCCloud's servers and linked.
Pro BNC by default
All other irc clients are only connected to the network as long as you are online. IRCCloud provides a bouncer by default, i.e. an irc proxy that maintains your presence and logs all chat. Said BNC remains online for 3 hours by default, papering over connectivity losses, or for a small fee of 4€ per month, you can remain online forever (good for travels and such).
Pro Cloud saving of logs
Never lose logs again, IRCCloud keeps them backed up and can email a zip of them to you on request.
Pro Amazing mobile app
Available on android and apple stores. It's just as good as the desktop client, comparable with discord though not as fully featured, being IRC.
Pro Prototype web wrapper client
There is a primitive, but consistently updated web wrapper that can act as a desktop client available on github. They don't exactly publicize it, but it is being actively developed all the same. It will likely evolve into a full-featured dedicated desktop client in time.
Pro Native emoji support
Pro Free tier
While IRCCloud is generally a subscription service, a limited free tier is available. It's limited to 2 external IRC networks besides irc.irccloud.com, accounts get disconnected after 2h while no frontend is used (does not apply for the first 7 days) and 100MB file sharing limit as well as it lacks a number of team and enterprise oriented features.
Pro Pastebin integration
IRCCloud will suggest putting long snippets of text on pastebin and link that instead of flooding the channel.
Pro Simple interface
IRCCloud has a simple two-pane interface with a chat window on the left and server and channel lists on the right. It includes colorized nicknames to easier tell users apart and allows customizing details such as clock format, usermode symbols and alerts.
Pro Takes security seriously
Offers bounties for reporting security bugs through HackerOne.
Pro Custom authentication support for enterprises
Pro On-premises hosting for enterprises
Pro Private servers for teams
Con Lack of bold, strikethrough, italic and color codes
This seems like something that should have been obvious.
Con Potential for networks blocking IRCCloud's connections
Since IRCCloud acts as a bouncer with all user connections coming from the same IP range, IRCCloud might be shut off from a network once a network's session limit is reached.