A login wall on every app
Each app lives on its own subdomain with its own session, so nothing leaks between them. Strangers hit the wall; invited people walk straight in.
Invite by email
Add someone to an app's member list and they're in — no redeploy, no account setup for them, no access-control code for you to write.
Apps that save data
Every app gets a scoped key-value and collections API, so a plain HTML page can store real data without a backend of its own.