Kestrel vs WCF: What are the differences?
Developers describe Kestrel as "Simple, distributed message queue system". Kestrel is based on Blaine Cook's "starling" simple, distributed message queue, with added features and bulletproofing, as well as the scalability offered by actors and the JVM. On the other hand, WCF is detailed as "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.
Kestrel can be classified as a tool in the "Message Queue" category, while WCF is grouped under "Realtime Backend / API".
Kestrel is an open source tool with 2.8K GitHub stars and 326 GitHub forks. Here's a link to Kestrel's open source repository on GitHub.