Serilog - Backend Development and Utilities
Raygun - Raygun gives developers meaningful insights into problems affecting their applications. Discover issues - Understand the problem - Fix things faster.
log4net - log4net is a tool to help the programmer output log statements to a variety of output targets.
Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.
Logary - Professional logging metrics and analytics for your apps
Kafka - Apache Kafka is publish-subscribe messaging rethought as a distributed commit log.