log4net - log4net is a tool to help the programmer output log statements to a variety of output targets.
Splunk - Splunk's operational intelligence platform helps unearth intelligent insights from machine data.
AWS CloudTrail - AWS CloudTrail is a web service that records AWS API calls for your account and delivers log files to you.
NewRelic - New Relic is a Software Analytics company that makes sense of billions of metrics across millions of apps. We help the people who build modern software understand the stories their data is trying to tell them.
Logary - Professional logging metrics and analytics for your apps
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.