Company-wise practice

Candidates commonly report a scale-first round. Expect very large numbers from the opening sentence, and be ready to justify a data structure choice in more detail than many rounds ask for. Interviewers often go deep on one subproblem rather than broad across the system.

Operational reality and cost. Who gets paged, what does this cost per month, how does it degrade, what happens on the busiest day of the year. Amazon publishes its Leadership Principles, and they often surface in the technical round too, particularly Ownership and Frugality.

Product sense plus very large fan-out. Expect social-graph shaped problems, expect the celebrity-user case to come up early, and expect to be pushed on what the user experiences rather than what the diagram says.

Often described as calmer and more collaborative than most. The round tests whether you can be reasoned with: expect the interviewer to propose an alternative and watch whether you engage with it or defend by reflex.

Often senior-heavy and direct. Expect few hand-holding questions, an assumption that you have run systems in production, and strong interest in failure modes, chaos testing and graceful degradation.

Real-time, geospatial and matching problems, because that is the business. Expect hard latency budgets, moving objects, and close attention to what happens when the match fails.