Icalingua++

Icalingua++ is a desktop client for the QQ instant-messaging network, packaged for Linux. It is maintained by Clansty and released under the AGPL-3.0-only licence, which means the source is available for inspection and modification, and that network-hosted derivatives carry the same obligation to publish their changes.

The entry describes it as a client for QQ "and more", which places it among third-party chat front-ends: it connects to an account on an existing service rather than providing messaging infrastructure of its own. The record does not enumerate protocol coverage, supported message types, or what is required to sign in, so anyone who depends on a particular capability should confirm it against the project's own documentation.

Scope is limited to Linux; no Windows, macOS, Android or iOS build is listed here. Because the client speaks to an external service, its behaviour is also affected by changes made upstream by that service's operator, which the maintainer does not control.