Anyone has any to recommend? I have heard of Hockey, Insights, and Firebase but these aren't free. I'm looking for free open source solution, something like ACRA for Android, preferably to report errors in an email but open for other means of reporting. I'm interesting in collecting primarily crash reporting providing call stack information but other useful reporting is more than welcome.
You could try RollBar. They have a free plan that allows for 5,000 events a month and retain data for 30 days. I use them at work and I actually really like them.
You can set which environment (dev, stage or production) the events are coming from.
You to keep track of code deployments, which then will allow you diagnose when the error started showing up.
They will email you a daily summary, and when an error starts occurring to many times within a few minutes.
I also found a GitHub project for hooking Rollbar up with Xamarin.