The team at TrackJS are really helpful. This is a quality product that will make any browser based product better.
When I started with TrackJS 7 months ago I wrote a Medium article explaining our integration with this tool, which has remained consistent to this point.
We moved all frontend applications to TrackJS and it has helped us to make incredibly helpful improvements, with impact measurements, fast feedback, alerts, filtering, groups, etc. We've run some benchmarks including other competitors, considering lots of aspects, and TrackJS was our best bet. And I'm really glad to endorse TrackJS - it has helped us a lot!
Have used this product for a couple of years now very pleased with it and get fast feedback with any issues