Rollbar - Rollbar collects errors that happen in your application, notifies you, and analyzes them so you can debug and fix them. Ruby, Python, PHP, Node.js, JavaScript, and Flash libraries available.
logstash - logstash is a tool for managing events and logs.
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.
rsyslog - Rsyslog is an enhanced syslogd supporting, among others, MySQL, PostgreSQL, failover log...
Logify - It is a real-time application monitoring and automated exception reporting.
Graylog - Graylog is an open source log management platform for collecting, indexing, and analyzing both structured and unstructured data.