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.
Splunk - Splunk's operational intelligence platform helps unearth intelligent insights from machine data.
Sumo Logic - Sumo Logic is a secure, purpose-built cloud-based machine data analytics service that leverages big data for real-time IT insights
Graylog - Graylog is an open source log management platform for collecting, indexing, and analyzing both structured and unstructured data.
logstash - logstash is a tool for managing events and logs.
Logentries - Log Management & Analytics Made Easy