TrackJS JavaScript Error Logging - JavaScript Error Monitoring from TrackJS gives you context about what's happening in your end-users' browsers.
PagerDuty - Cloud based monitoring service
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.
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams
CatchJS - Unbloated, yet feature rich. CatchJS provides JavaScript Error Tracking the way it should be.
Squadcast - Automate incident response, reduce downtime and enhance your tech teams’ delivery with a unified platform.