More about the 5 Best Frontend Error Monitoring Tools.
Raygun and BugSnag are both full-featured error tracking and real user monitoring platforms catering to enterprise customers. Raygun provides better support while BugSnag has better noise controls. For a cheaper, front-end error tracking alternative with both great support and noise control, consider TrackJS.
With TrackJS, the focus is on errors occurring on the browser. Filtering is second to none, and the quick views of trending errors are helpful in digging past the 3rd party script noise. It filters down to the core issues.