A full list of what to track for your applications and services will vary, but here are some basic KPIs to get you thinking in the right direction: Number of conversions or number of “dollar making” interactions; User experience score; Percentage of crash-free users (mobile specifically); Google Core Web Vitals: Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift (specifically for web); Availability and Response Time of API (specifically for API driven industries); Net promoter score; Number of failing form field validations; Number of displayed error messages