SoftHSM
SoftHSM is an implementation of a cryptographic store accessible through a PKCS #11 interface. You can use it to explore PKCS #11 without having a Hardware Security Module. It was originally developed as a part of the OpenDNSSEC project. SoftHSM uses Botan or OpenSSL for its cryptographic operations.
Source Code
All source code can be found on GitHub.
Bug Reporting
Bugs in SoftHSMv2 are reported on GitHub.