Instabug!

Rollbar collects errors that happen in your application, notifies you, and analyzes them so you can debug and fix them. JavaScript, Ruby, Python, PHP, Node.js, Android, Flash, .NET, and Java libraries are available.

Light weight crash reporting solution, we find the needle in the haystack, even the exact line of code that your app crashed on.

Bugsnag automatically detects errors in your mobile, front-end, and back-end applications, and provides your team the tools to fix things fast. Bugsnag provides clear insights on the frequency and user impact of each error, so your team can make informed prioritization decisions. Replicating and troubleshooting is easier with automatically collected diagnostic data on where and how an error occurred. Over 3,500 of the world's best engineering teams from organizations like Square, Airbnb, Shopify, and others use Bugsnag to build better software. »

Airbrake collects errors generated by other applications, and aggregates the results for review.

SessionStack helps you see your web app defects through a user’s eyes.

RootCause provides you with a comprehensive set of tools to monitor and reproduce errors in web sites/applications. Using the built-in recorder feature you’ll know exactly what the user did. After an error has been logged, head over to the web-based Replay Studio where you can replay the session to reproduce the error with one click.