Meta
- Discourse Meta: https://meta.discourse.org/
Apps
- AntennaPod Forum: https://forum.antennapod.org/
- K-9 Mail: https://forum.k9mail.app/
- Nextcloud Community: https://help.nextcloud.com/
- Signal Community: https://community.signalusers.org/
- Syncthing Community Forum: https://forum.syncthing.net/
Phone manufactures
- Fairphone Community Forum: https://forum.fairphone.com/
Free software
- FSFE Community: https://community.fsfe.org/
Security and privacy
- [German] Kuketz IT-Security Forum: https://www.kuketz-forum.de/
Developer & Build tools
- GitLab Forum: https://forum.gitlab.com/
- Gradle Forums: https://forum.gitlab.com/