Bitrix24
Free all-in-one business suite: CRM, project management, tasks, telephony, and team collaboration in a single platform.
Bitrix24 packs a full CRM, project management, telephony and collaboration stack into one platform that stays free for unlimited users, then scales on flat per-organization pricing instead of charging per seat. The dense, do-everything interface carries a real learning curve, but for a growing team that wants to replace five separate tools it is a clear Strong Buy.