More about the 5 Best Frontend Error Monitoring Tools.
Rollbar provides error monitoring to fullstack teams. Raygun is a full featured APM service for big enterprise. Raygun has more breadth, and capability, but is more expensive than Rollbar. For a cheaper, front-end error tracking alternative, 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.