Why these together

This stack is the minimum viable replacement for a Slack + Notion + Asana + Zoom + 1Password setup, picked for low operational overhead rather than feature parity. Mattermost is the Slack-clone everyone expects; Outline is the Notion piece that ports cleanly via Notion's own export; Vikunja is the boards-and-tasks app most teams find tolerable to administer; Jitsi handles ad-hoc rooms (no scheduled-meeting scaffolding — pair with Cal.com if you need that); Vaultwarden is the credentials vault that closes the only remaining 'we still pay a vendor' line. All five run inside a docker-compose on a $20 VPS for teams up to ~25, and each authenticates against a single Authentik or Keycloak if you decide to add SSO later.