HubSpot CRM - Free CRM software for small businesses.
Zendesk Sunshine - Open, flexible CRM platform built on AWS
Bigin by Zoho CRM - Pipeline-centric CRM built and priced for small businesses
Crmble - Easy peasy crm for Trello
InStream CRM - Business relationship management platform - CRM alternative
erxes Mobile - Some of the most important CRM and web chat tools on the go