HubSpot CRM - Free CRM software for small businesses.
Onesheet CRM - The Simple CRM for Google Sheets
Bigin by Zoho CRM - Pipeline-centric CRM built and priced for small businesses
Followup.cc - FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Set perfectly timed reminders that arrive at the top of your inbox, right when you need them.
erxes Mobile - Some of the most important CRM and web chat tools on the go
Freshsales CRM - A full-fledged CRM for high-velocity sales teams.