HubSpot CRM - Free CRM software for small businesses.
EspoCRM - EspoCRM is open source CRM (Customer Relationship Management) software that allows you to see, enter and evaluate all your company relationships regardless of the type.
Bexio - Bexio helps small businesses manage their accounting, contacts and inventory.
CiviCRM - A Constituent relationship management for the Civic Sector
Flowlu - Flowlu provides business management software, project management, agile project management and collaboration tools for teams of all sizes.
Less Annoying CRM - A simple customer relationship manager made just for small businesses. Manage contact info, track leads, and never miss a follow-up.