Conduct back-of-the-envelope estimations to justify your database choices. Phase 3: Design Deep Dive (15–20 minutes)

You cannot design a system without numbers. Alex provides a cheat sheet you must memorize.

Moving session data out of web servers into centralized stores (like Redis) so any server can handle any incoming request. 4. Key Case Studies to Memorize

: This is the official online platform created by Alex Xu that includes the content from his books plus regularly updated deep dives into new system architectures. The 4-Step System Design Framework

If you cannot find a legitimate copy of the Alex Wu PDF (due to copyright or access issues), the industry consensus places these resources as "Tier 1" alternatives that use the exact same methodology :

Draw a basic end-to-end architecture connecting clients, API gateways, application servers, and databases.

Which (e.g., WhatsApp, Uber, Netflix) do you find hardest to design?

Tools like Kafka or RabbitMQ handle asynchronous tasks, decouple services, and smooth out traffic spikes.

The Ultimate Guide to Ace Your System Design Interview: Why Everyone Searches for Alex Xu's Material

System Design Interview – An insider's guide, Second Edition