For private sites just use your own CA. Also the server for LetsEncrypt is open source [1] and comes with test scripts to run it during development and testing

For private sites just use your own CA. Also the server for LetsEncrypt is open source [1] and comes with test scripts to run it during development and testing to avoid premature exposure to the public instance of LetsEncrypt. [1] https://github.com/letsencrypt/boulder https://github.com/letsencrypt/boulder