Best freelance availability calendar for agencies

There are roughly 12-18 tools that touch some part of freelancer availability management (Upwork, Fiverr, Togal, Kimble, Mavenlink, Float, and niche calendar apps), but almost none were built specifically for agencies managing distributed freelance teams across multiple clients simultaneously. The real pain point isn't scheduling—it's the gap between real-time availability visibility and project demand forecasting. Agencies waste 4-6 hours per week manually syncing availability across tools, and freelancers get overboooked or left idle because there's no single source of truth. The actual opportunity sits at the intersection of resource planning + availability calendars + client communication—a shipper needs to build something that lets agencies see freelancer capacity in real-time, forecast demand three sprints ahead, and automatically surface conflicts before they blow up a project. Most existing tools prioritize the freelancer's side or the client side, but not the agency's middle position. A new entrant should obsess over the scheduling-to-billing handoff: the calendar needs to feed directly into project tracking, timesheets, and invoicing without manual data entry.