Bitrix24

Bitrix24 is a vast, free-tier collaboration platform that includes a fully-featured CRM. Beyond contact and deal management, it incorporates tools for tasks, projects, document management, messaging, video calls, and a company social intranet. Its CRM includes telephony, marketing automation, and helpdesk. The free plan supports unlimited users with core features, making it attractive for startups and small teams on a tight budget.

It's ideal for organizations looking for a single digital workplace that blends CRM with internal communication and project management. Its ranking acknowledges its incredible breadth and value, though its interface can be complex due to the sheer volume of features.