Onesheet CRM - The Simple CRM for Google Sheets
Crmble - Easy peasy crm for Trello
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.
Freshsales CRM - A full-fledged CRM for high-velocity sales teams.
Zoho CRM - Omnichannel CRM for Businesses of all sizes
Pipedrive - Sales pipeline software that gets you organized. Helps you focus on the right deals, so easy to use that salespeople just love it. Great for small teams.