API server documentation


I have read RFC 8555 and
I would like to write a custom LE client, but I can’t find LE API server ( https://acme-v02.api.letsencrypt.org/directory ) documentation.

Can someone point me to the right documentation point telling client how to communicate with server ?

Hi @winnie,

The Let’s Encrypt API service at the URL that you mentioned is an RFC 8555 service implementation. In particular, it’s a directory instance as mentioned in section 7.1.1 of the RFC.


What kind of additional documentation are you interested in?

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Hi @schoen,

I’d like to know is there any official document released from LE to developer?
The document should include every API input message and output message definition.

RFC8555, linked above, is that official document. All the client developers made their clients by referencing it.

If you don’t want to go to the trouble, there are ACME libraries for practically every programming language and runtime available.

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What would the extra benefit be for such an API documentation, compaired to the RFC? The RFC contains all the (textual) nuances such a list of input/output messages would miss. I don't think one would be able to properly build an ACME client with just a list of input/output messages.

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