Jeremie_L
Sentry is used for Application performance and error monitoring.
The free tier allows up to 5,000 errors (exception reports) per month, it took me almost two years of using Sentry to exceed that limit.
The greatest advantage in my point of view is error grouping which helps working on most urgent errors first.
I know many of us have written their own error report tool, even I did. But re-inventing the wheel is time consuming 
Exceptions are sometimes very difficult to reproduce. The amount of information sent to Sentry with each error report has been a huge help in fixing some exceptions.
Such as seeing that exception X only happens on Windows, or exception Y only happens to users running the app in Spanish.
Error reports can be completely anonymous which makes it GDPR compliant.
Here is what a Sentry error report looks like:
But that is only a small portion of the report.
Here is what I see below the fold:
Breadcrumbs allow me to see exactly what happened before the exception.
File attachment and screenshots can also be sent with exception reports.
Tags and Key/Value pairs can be added, for example to return the parameters of a URLConnection.ContentReceived event and understanding why an exception happened.
Don’t want to derail this topic so I will be opening a new one for discussing Sentry very soon.