All IRMA software is open source and can be found at https://github.com/privacybydesign. (Almost) all projects have README’s that explain their use. Other technical documentation can be found here:

• </attribute-index/en/>
  A searchable list of all issuers, credentials and attributes that are currently in the IRMA domain, as known to the Privacy by Design Foundation.
• https://credentials.github.io/
  Short general introduction to the core software projects and protocol.
• https://credentials.github.io/docs/irma.html
  A comprehensive introduction to key concepts, the main functionality and of the security properties of IRMA.
• https://credentials.github.io/protocols/irma-protocol/
  Description of the IRMA protocol used in IRMA sessions.

Source code of legacy and unmaintained IRMA software projects is still available at https://github.com/credentials.