Charybdis is a highly scalable IRC server which presently implements the IRCv3.1 client protocol with some additional components of IRCv3.2. Development of charybdis began in 2005 as a proposed replacement to freenode’s hyperion ircd, designed for use by any network, with roots in ircd-ratbox and ircu. Over time, charybdis has developed, tested and demonstrated many of the features commonly seen in modern IRC networks.

Interesting features that Charybdis has include:

* SASL support — charybdis was the first IRC server to implement SASL
support, resulting in the IRCv3 SASL standards.
* DNS blocklist support
* Augmented banlist criteria through “extbans”
* Channel forwarding (channel mode +f)
* Optional hostname/IP cloaking (through modules, either usermode +h or
+x)
* Colorcode stripping (channel mode +c)
* CALLERID (user mode +g) with automatic accept when you send a PM
* TLS encrypted client and server connections
* Multi-process sandbox architecture for enhanced security, scalability
and robustness
* Easy to understand configuration
* A complete user and operator’s manual
Many of the largest networks in the world use charybdis-based IRC servers, including freenode, EsperNet, DarkMyst and others, because of it’s proven scalability, security and robustness track records