EJBCA is an enterprise class PKI Certificate Authority built on JEE technology. It is a robust, high performance, platform independent, flexible, and component based CA to be used standalone or integrated in other JEE applications.
Plug-and-Play Certification Authority is java implementation of Certificate Authority with web interface. It requires minimal setup and no extra database - it is pnp. It originally has been developed as a part of Unicore (http://www.unicore.eu/) suite.
CertForge is a web-based certificate utility written in Java 1.6, to make or view X.509 certificates, keys, CRLs, manage keystore and truststore (CTL) for SSL sites, and run as a simple Certificate Authority (CA).