Custom Domain HTTPS on Read the Docs: Unresolved Wildcard Certificate Support

Goal

To understand the current limitations and future plans for serving multiple subdomains under a single custom domain on Read the Docs using HTTPS.

Constraints

Read the Docs automatically issues a free Let's Encrypt certificate for each custom domain that points to readthedocs.org via a CNAME (or an A/ALIAS record for apex domains). The platform does not support wildcard certificates, meaning each subdomain must have its own record and certificate. This restriction can complicate deployments that require a single domain to host many sub‑domains.

Unresolved Questions

• Will Read the Docs introduce wildcard certificate support in upcoming releases?
• If wildcard support remains unavailable, what alternative configurations can enable HTTPS for many subdomains without individual certificates?
• Are there plans to support CNAME flattening or similar mechanisms for apex domains to simplify certificate provisioning?