OroCRM
- github.com/orocrm/crm-application
- It should nice integrate with Magento 2.
- It is a CRM only! There is no accounting and product management functonality.
Odoo
- github.com/odoo/odoo
- The date of the first GitHub commit: 2007-03-25.
- It is written in Python.
- The CRM is a part of the Odoo ERP suite.
EspoCRM
It looks very good.
SuiteCRM
- github.com/salesagility/SuiteCRM
- The date of the first GitHub commit: 2013-09-22.
- I do not like its source code.
- It is a fork of SugarCRM.