If you want to pass the interview, buy the course. But if you want to it—to truly understand the gestalt of scaling a system from zero to billions of users—follow the GitHub trail.
That is where the real learning happens. Not in the paid course, but in the public, messy, brilliant fight to fix the diagram. Recommended GitHub search to start your journey: system-design-primer (by donnemartin) – the unofficial king of the hill. grokking the system design interview github
The GitHub repos have responded. The best forks now include sections—the dirty details the original paid course glossed over. The Verdict GitHub has become the annotated bibliography for Grokking the System Design Interview . It is where the rote memorization of the course meets the practical, messy reality of open source collaboration. If you want to pass the interview, buy the course