letsencrypt-helper

Generates and keeps up-to-date your Spring Boot applications' Let's Encrypt or other ACME compliant SSL certificates. Pure Java in a single file of library code. An automated embedded alternative to Certbot and docker-sidecars. No JVM restart is needed on certificate update. Maintained by valb3r on GitHub, where it has earned 48 stars from the community.

It's actively developed around spring-boot, java, tomcat, and is a solid reference for anyone building with these tools.