SignalR vs WCF: What are the differences?
What is SignalR? A new library for ASP.NET developers that makes developing real-time web functionality easy. SignalR allows bi-directional communication between server and client. Servers can now push content to connected clients instantly as it becomes available. SignalR supports Web Sockets, and falls back to other compatible techniques for older browsers. SignalR includes APIs for connection management (for instance, connect and disconnect events), grouping connections, and authorization.
What is WCF? A runtime and a set of APIs for building connected, service-oriented applications. It is a framework for building service-oriented applications. Using this, you can send data as asynchronous messages from one service endpoint to another. A service endpoint can be part of a continuously available service hosted by IIS, or it can be a service hosted in an application.
SignalR and WCF can be primarily classified as "Realtime Backend / API" tools.
SignalR is an open source tool with 7.75K GitHub stars and 2.19K GitHub forks. Here's a link to SignalR's open source repository on GitHub.
According to the StackShare community, SignalR has a broader approval, being mentioned in 22 company stacks & 18 developers stacks; compared to WCF, which is listed in 8 company stacks and 3 developer stacks.