CiviCRM - A Constituent relationship management for the Civic Sector
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
WORKetc CRM - All-in-one business management system. CRM + Social + Projects + Billing
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Pipeliner CRM - Pipeliner CRM empowers small to medium-sized sales teams to close more deals and lower risk. Implementation and training are a breeze. Mac & Windows.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.