Interviews on Mobile System Design (MSD) are becoming a crucial part of selecting engineers in mobile development. They typically last no more than an hour but involve broad, intentionally open-ended questions such as: "Design Facebook," "Create a library for pagination," or "Design YouTube." In the limited time available, it's important to quickly clarify requirements and focus on the key aspects of the task.
Why Companies Conduct MSD Interviews
These interviews fill a gap not covered by algorithmic and data structure tasks. While algorithmic interviews assess coding skills, design questions evaluate senior-level skills:
- The ability to work with uncertainty and formulate requirements;
- The capability to break down complex tasks into components;
- Depth of technical knowledge and systemic thinking;
- Understanding of trade-offs and architectural solution options;
- Communication and teamwork skills.
MSD interviews are specifically designed to have no single "correct" answer. In some cases, your line of reasoning is more important, while in others, solutions close to industry standards or the company’s internal architecture are expected. The key is to demonstrate a structured approach, justify your choices, and clearly explain trade-offs.
Unlike algorithmic interviews, MSD rarely require writing code. At most, schematic pseudocode or a description of data exchange between components is needed. The main focus is on architecture, design decisions, and your ability to think like a systems architect.
