Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
SignalR - SignalR is a server-side software system designed for writing scalable Internet applications, notably web servers.
Supabase - An open source Firebase alternative
Scaledrone - Realtime messaging service
Etebase - Etebase makes it easy to build end-to-end encrypted applications by taking care of the encryption and its related challenges.
Entity Signal - Real Time Entity Framework (EF) and ASP.NET core. Make all of your data real time.