Short answer: Doorkeep works without any PMS integration. The integrations that exist today are in Beta and connect only.
Buildium, Rentvine, and DoorLoop
All three are in Beta and are connect only. In Settings, under Integrations, you can click Connect on your PMS and Doorkeep tests the connection with your API credentials. Nothing syncs between Doorkeep and your PMS, and Doorkeep does not log calls or create work orders there. The descriptions on that page mention syncing; that is not available. Treat these as early access rather than a finished integration.
AppFolio
Not supported, and not on the near-term roadmap. If an AppFolio integration is a requirement for you, I would rather say so now than sell around it.
Getting your data in today
You can import tenants and contacts from the Contacts page: upload a CSV, Excel (.xlsx), or vCard file, or paste a list, and AI-assisted column mapping sorts out the fields. Your import is what lets Doorkeep recognize callers and properties.
You do not need an integration to use Doorkeep
Doorkeep answers calls, detects emergencies, connects callers to your Call List with a briefing when your setup calls for it, and documents every call, all without touching your PMS. The integrations are not a prerequisite.
If your PMS is not listed and you want to talk through what would work, book a call.