Vercel Sandbox can now connect to hosted Postgres databases, including Neon , Supabase , AWS RDS , Nile , and Prisma Postgres . To enable a connection, add the database host to your Sandbox's allowed domains. Link to heading Background When SNI based filtering is used with Vercel Sandbox, the sandbox firewall restricts outbound network access by checking the domain name during a connection's TLS handshake. This works seamlessly for HTTPS traffic, where the domain is visible at the start of the connection. Postgres, however, negotiates TLS differently. A Postgres client first opens a plain TCP connection and then upgrades to TLS. Because the domain isn't available when the firewall first needs it, Postgres connections through a standard domain-restricted Sandbox would fail. Link to heading What changed The Sandbox firewall now adjusts for the Postgres TLS negotiation flow.…