Wikipedia
PJIRC
Plouf's Java IRC (PJIRC) is a web-based open source IRC client that is written in Java. Any web browser that supports the Java Runtime Environment, or an alternative Java interpreter, can use the applet. Many IRC networks have a public installation of the applet for their network.
Philippe Detournay, the initial and main contributor, has stopped working on the project since 2005. However, the website forum is still frequently used and moderated by the administrators.