You can find all source code for IdentityServer and its supporting repos in our organization.
The IdentityServer issue tracker and pull requests allow you to follow the current work and submit questions or bug reports.
See here for our support policy.
Standard support and feature requests are handled via our public support forum. Please start a discussion there if you need help.
Priority support is part of our Enterprise Edition. It includes a private email alias, guaranteed two US business days response time.
Security issues and bugs should be reported privately here. You should receive a response within 24 hours.