See What Your Users See

Most dashboards tell you when your servers are healthy. Few tell you when your users are happy. This book bridges that gap.

From first principles to production-grade SDKs, you'll learn to build UserGazer — a complete frontend observability system that captures what users actually experience in the browser.

Step by step, each chapter expands your understanding: Capture Core Web Vitals, errors, and interactions. Correlate signals with privacy-safe sessions. Export data reliably, even when offline. Visualize what happened — and why.

You'll walk away with a working open-source SDK (UserGazer v0.7) and, more importantly, a reusable mental model: Capture → Enrich → Normalize → Export.

Whether you're a frontend engineer, SRE, or product lead, this book helps you move beyond "page views" — to truly see what your users see.