Yac - Take your time back from Zoom & Slack
Sync.com - Sync. com offers a backup tool and a file sharing service, rolled into one.
Echoes - Voice-first messaging for fast & collaborative remote teams
Zoho WorkDrive - File storage & content collaboration tool for modern teams
WebRTC - WebRTC is a free, open project that enables web browsers with Real-Time Communications (RTC) capabilities via simple JavaScript APIs. The WebRTC components have been optimized to best serve this purpose.
kDrive - The most privacy-friendly online storage and file sync service. From 2 TB, hosted in Switzerland.