To ensure fair use of the service by as many people as possible, Let's Encrypt offers rate limiting. We believe these rate limits are high enough for most people to use by default. Let's Encrypt rate limits certificate issuance to ensure that as many people as possible can reasonably use our service. We believe these rate limits are adequate for users in most cases. Also renewing certificates is virtually immune to rate limiting, so large organizations can incrementally increase the number of certificates they can issue without Let's Encrypt's intervention.
Our main constraints areThe number of certificates that can be issued for each registered domain name (50 per week). Generally speaking, a registered domain name is that portion of a domain name that you purchase from a domain registrar. For example, in www.example.com , the registered domain name is example.com. In new.blog.example.co.uk , the registered domain name is example.co.uk. We will use the public suffix list to calculate the registered domain name. Requests that exceed the limit on the number of certificates that can be issued for each registered domain name will receive an too many certificates already issued error message and may provide other information.
If you have many subdomains, you may want to combine them into one certificate, limited toUp to 100 domain names per certificate . Linked to the limit above, this means that you can apply for certificates for 5,000 different subdomains per week. Certificates with multiple domain names are often referred to as Subject Alternative Name (SAN) certificates, or sometimes Unified Communications Certificates (UCC). Note: For performance and reliability reasons, it is recommended that each certificate contain as many