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.
HubSpot CRM - Free CRM software for small businesses.
CiviCRM - A Constituent relationship management for the Civic Sector
Keap - Grow Sales. Save Time. Get Organized.
Less Annoying CRM - A simple customer relationship manager made just for small businesses. Manage contact info, track leads, and never miss a follow-up.
WORKetc CRM - All-in-one business management system. CRM + Social + Projects + Billing