Through the comment from @jsha , I noticed there’s another acme-spec repo existing on github. Now my question: Where should we place our issues related to the acme-spec on github? What’s the reason for the ietf-wg-acme/acme repo?
Looks like coolaj86 already asked nearly the same thing in the ietf-wg-acme/acme repo  but it’s still a bit confusing.
Hi @mrmstn, the letsencrypt version is the specification that the Let’s Encrypt CA is implementing, while the ietf-wg-acme version is the specification that the IETF ACME working group is standardizing.
In the long run I’d expect these should be fully compatible with one another (if not identical), but that isn’t guaranteed to be true at a particular point in time and Let’s Encrypt may launch with an implementation of something that differs in some respects from the working group’s then-current draft.
@mrmstn: Sorry for the confusion, and sorry for the late reply. Please file issues and pull requests on the ietf-wg-acme repo. I would also encourage you to join the IETF ACME mailing list and make comments / participate in discussion there.
Would be nice if the IETF ACME repository was more active.
Is there a referenced version of the spec that Letsencrypt implements, with what functionality is implemented & what is left to do? A simple table with this info would be very useful indeed, especially to ACME client authors, considering Letsencrypt is by far the most widely used implementation.