Akamai is integrating with Let's Encrypt and has plans to make their
certificates available to our customers. During the early testing
period we will be creating certificates and exercising the API and out
provisioning code. We may be looking for customers who would like to
try out this beta offering.
https://community.akamai.com/thread/2782
According to their principal engineer this will be generally available in Q4:
https://twitter.com/RichSalz/status/657630838339817472