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.

Rayfeed - Improve your product with video and audio feedback 📹🔊

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.

SessionStack - Record and replay web app issues. See them the way they happened to end users.

RootCause - Record, Replay and Reproduce JavaScript Errors

Instabug - The top apps in the world rely on Instabug for beta testing, user engagement and crash reporting.