certbot formerly letsencrypt client for Lets Encrypt Certificates
Certbot (previously, the Let's Encrypt client) is BETA SOFTWARE. It contains plenty of bugs and rough edges, and should be tested thoroughly in staging environments before use on production systems.
For more information regarding the status of the project, please see https://letsencrypt.org. Be sure to checkout the Frequently Asked Questions (FAQ).
Certbot is a fully-featured, extensible client for the Let's Encrypt CA (or any other CA that speaks the ACME protocol) that can automate the tasks of obtaining certificates and configuring webservers to use them. This client runs on Unix-based operating systems.
Until May 2016, Certbot was named simply letsencrypt or letsencrypt-auto, depending on install method. Instructions on the Internet, and some pieces of the software, may still refer to this older name.