- libltdl >= 2.2 (part of GNU libtool)
- sqlite >= 3.8 (default database, required)
- mysql >= 5.1 (alternative to sqlite)
-- postgres >= 9.6 (alternative to sqlite)
+- postgres >= 9.5 (alternative to sqlite)
- libopus >= 1.0.1 (optional for experimental conversation tool)
- libpulse >= 2.0 (optional for experimental conversation tool)
- libogg >= 1.3.0 (optional for experimental conversation tool)