Sentry

Sentry is an error tracking and application performance monitoring tool built for production apps and SaaS products. It is made by the company of the same name and is used by teams ranging from solo startups to giants like GitHub, Disney and Reddit. It is for anyone running a live website or app who wants to know what is actually breaking for their users.

It works simply: you add a small piece of code to your app (an SDK for JavaScript, Python and dozens of other languages and frameworks) and from that moment Sentry captures every exception, crash and error your users trigger. The input is errors from the browser, server and mobile; the output is a clear list of issues sorted by impact, with full context — which line of code failed, on what device, in which browser, and how many people were affected.