RedHen - CRM built on Drupal

RedHen is a Drupal-native CRM initially designed for common nonprofit needs, but built for flexibility. It has classic CRM functionality for managing information about contacts, organizations, and their relationships between each other and your organization (like memberships). It also knows some modern tricks (like engagement tracking), and stuff you'd hope for in a website-integrated CRM (like event registration integration).

RedHen can help you track relationships and interactions with people and organizations, and since it's integrated with your website it can allow you to use that information to change the way your site behaves and the way your users interact with it. A simple example is connecting Contact records in the CRM to a Users in Drupal, so if your contacts have a login to your site they can update their mailing address when they are logged in, and that information goes into your CRM database automatically.