Kontact - Kontact is the integrated Personal Information Manager of KDE.
Zoho CRM - Omnichannel CRM for Businesses of all sizes
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
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.
Duplicate Contacts Fixer and Remover - Duplicate Contacts Fixer and Remover app enables users to merge all the duplicate contacts as well as they can also delete duplicate entries with a single tap.
Copper - Copper (formerly ProsperWorks) is easy-to-use customer relationship management for small businesses. Capture contacts and sales leads direct from Gmail with our simple CRM.