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.