Apogee Watcher vs PostHog Web Vitals: Synthetic PageSpeed Monitoring and Product Analytics Compared

Core Web Vitals show up in two different places. One is real users: metrics from the browser, fed by an analytics SDK. The other is scheduled tests: Google’s PageSpeed machinery runs on a URL you choose, on a cadence you set. PostHog is the first kind for performance. Its Web Vitals live under Web Analytics and use the same posthog-js SDK as the rest of product analytics. Apogee Watcher is the second kind: multi-tenant PageSpeed monitoring on the PageSpeed Insights API—Lighthouse lab data plus CrUX where Google publishes it—for teams covering many sites without putting a script on every domain. PostHog is a strong product stack (flags, replay, experiments, warehouse analytics). We are not building that. PostHog’s Web Vitals module also does not replace synthetic monitoring for sites you never instrument, and it does not include Watcher’s automated discovery, performance budgets, or agency RBAC by default. The decision is which problem you are solving first—and whether you need both. Wh