Fat Free CRM (customer relationship software) is an open-source software that's built to give businesses a user-friendly front-end application for managing their day-to-day customer interactions. The software comes with default features for managing group collaboration, campaigning, sales leads, and opportunity tracking. Built on Ruby on Rails, Fat Free CRM gives developers a customizable interface with well-documented guides to speed up "go-live." Fat Free CRM is designed for small teams to handle a large amount of tasks. The open-source software has intuitive built-in models that allow users to efficiently create campaigns, manage contacts, and assign accounts. Additionally, plugins are available for businesses to customize fields and filters, send service hooks, integrate Google calendar, enable mass mailing, time track projects, and import data from mapped sources like Salesforce. Using Ruby on Rails, IT developers can easily create customized plugins to work with Fat Free CRM to meet their business needs.