What database should sit under my AI-built internal tool: Supabase, Airtable, Postgres, or a spreadsheet?

Supabase (managed Postgres) has become the default under AI app builders because it gives you real SQL, logins, and APIs with zero server admin, and every major builder connects to it. Airtable or Notion are fine while data is small and humans are the main interface; the tell that you have outgrown them is concrete: slow views, automation-run limits, manual export rituals, or a price cliff. Whatever you choose, keep it exportable: plain Postgres underneath means you are never locked into the builder that created it.

A quick orientation. The real value is below: resources worth your time, from people who've actually done it.