System Design Interview – BIGGEST Mistakes to Avoid

In summary, the most interesting aspect is the emphasis on right-sizing technical solutions to match actual scale and requirements, rather than defaulting to over-engineered architectures that ignore practical constraints.

• Think out loud and narrate your reasoning to communicate your process.
• Always start by clarifying functional and non-functional requirements.
• Begin with high-level architecture before diving into implementation details.
• Explicitly discuss trade-offs when choosing technologies or approaches.
• Match system complexity to actual scale to avoid over-engineering.
• Treat system design as a collaborative problem-solving exercise under constraints.