Glossary

Custom domains glossary

These are plain-English definitions of the concepts behind custom domains for SaaS. If you are letting your end customers bring their own domains onto your product, these are the ideas you will meet along the way. Each entry links to a fuller definition, and the guides below show how the pieces fit together in practice.

Definitions

• Bring your own domain (BYOD). Letting each customer serve your product on a domain they own, such as app.acme.com, instead of a subdomain of yours.
• Multi-tenant TLS. Serving valid HTTPS certificates for many customer domains from one shared platform, so every tenant gets a padlock without managing its own.
• Apex domain vs CNAME. Why a bare root domain like acme.com is handled differently from a subdomain like app.acme.com when you point it at your platform.
• On-demand TLS. Issuing a certificate automatically at the moment a customer domain first receives traffic, rather than provisioning every certificate up front.

Developer guides

• How to add custom domains to your SaaS. The end-to-end flow, from collecting a customer domain to verifying ownership and routing traffic.
• How to automate TLS for customer domains. How certificates are issued and renewed over ACME so HTTPS just works for every tenant.
• How to let AI agents connect domains. Exposing domain connection over MCP so an agent can wire up a customer domain on the user's behalf.

For the full picture, read the complete guide to custom domains for SaaS.