The core application uses a LAN or the Internet to connect to one or more clients, and also various IRC servers.

This system is similar to what Irssi, WeeChat with GNU Screen,[10] and Smuxi[11] use.

[12] Quassel stores discussion history in either a PostgreSQL or a SQLite database.

The connection between the client and the core can be encrypted using Secure Sockets Layer (SSL), and proxies are supported.

[7] In a 2009 roundup of large IRC clients for Tom's Hardware, Adam Overa described Quassel as being "fully featured" with "tons of options", and said "even new users should have no problem connecting to servers and finding channels using the GUI tools for server presets and channel lists.