Are System Design questions part of the L4 interview at Google?

System Design interviews are a critical part of the hiring process for many software engineering roles. But if you're applying for an L4 (mid-level) position at Google, you might be wondering: Does Google ask System Design interview questions for L4? The short answer: it depends. 

Let's break it down.

Understanding the role of an L4 engineer#

L4 engineers at Google are expected to be strong individual contributors. Their primary responsibilities typically include:

• Writing clean, efficient, and maintainable code

• Solving algorithmic problems effectively

• Collaborating with teammates to build scalable solutions

• Contributing to design discussions without necessarily leading them

Unlike L5 (Senior Engineers), L4s aren’t expected to own large-scale architecture decisions. But that doesn’t mean System Design is completely off the table.

When might System Design for L4 at Google be asked?#

While not a guaranteed part of the L4 interview process, System Design questions can still appear under certain conditions:

• Backend-heavy roles: If the team you're interviewing with builds infrastructure or backend systems, interviewers may want to assess your foundational understanding.

• Relevant past experience: If your resume shows prior involvement with scalable systems or design work, it may prompt follow-up questions.

• Team-specific needs: Teams like Google Cloud or Google Ads may ask you to design basic scalable systems, even at L4.

• L4.5 signal: If your interview performance suggests you’re close to L5, a lightweight System Design question may be introduced to evaluate your readiness.

What kind of System Design questions could you face?#

If System Design is part of your interview, expect scoped-down versions of L5+ questions. These might include:

• Design a URL shortener: Discuss database schema, scaling reads/writes, and key generation.

• Design a caching layer: How would you reduce latency? How do you handle invalidation?

• Design a rate limiter: What techniques would you use to prevent abuse under heavy traffic?

• Design a messaging queue: Explain message durability and failure recovery.

Interviewers won’t expect a production-ready blueprint. But you should demonstrate a solid grasp of key concepts like:

• Load balancing

• Data partitioning (sharding)

• Cache strategies

• Read vs. write optimization

How to prepare for System Design as an L4 candidate#

Even if System Design doesn’t come up, being ready is always a good bet. Here's how to prepare effectively:

• Master the fundamentals: Know the CAP theorem, consistency trade-offs, and common design patterns.

• Think in components: Focus on high-level APIs, queues, databases, and load balancers rather than low-level internals.

• Prioritize trade-offs: Be ready to explain why one approach might be better than another depending on scale, latency, or cost.

• Study simplified architectures: Look at how products like YouTube, Twitter, or Google Docs manage scalability.

Common pitfalls in System Design interviews#

Here are common mistakes candidates for the Google L4 position make when System Design enters the conversation:

• Jumping into code too soon: Design interviews are about architecture and trade-offs, not implementation.

• Ignoring scale: Even simple services should account for growth over time.

• Failing to communicate trade-offs: A correct answer without justification won’t score well.

• Overengineering: Simplicity wins—don’t introduce components unless they serve a purpose.

How Google evaluates System Design skills at L4#

If you're asked a System Design question as an L4 candidate, Google may assess:

• Clarity of thought: Are your ideas structured and easy to follow?

• Scalability: Do you understand how traffic growth affects your design?

• Efficiency: Are your storage, compute, and data flow choices appropriate?

• Trade-offs: Can you defend your decisions under alternative constraints?

The bar is lower than L5, but the signals still matter.

The role of System Design in Google’s tech stack#

Even at L4, understanding Google’s infrastructure gives you valuable context. Here are a few systems worth researching:

• Spanner and Bigtable: Distributed databases used across Google’s backend.

• Colossus: Google’s scalable storage system.

• Borg and Kubernetes: The backbone of container orchestration.

While you won’t be expected to design Colossus, knowing how real-world distributed systems work at scale can improve your interview performance.

Real experiences from L4 candidates#

Many L4 candidates report that System Design didn’t appear in their interviews, but those who mentioned scalable systems on their resumes were occasionally asked about them. What we can learn:

• Coding dominates: Expect DSA and algorithmic questions to be the focus.

• Lightweight design can appear: Especially if your experience or team requires it.

• Recruiter guidance matters: Ask your recruiter if System Design will be covered so you can focus your prep.

Best resources to learn System Design for L4 at Google#

If you want to prepare without going too deep, try these:

• Designing Data-Intensive Applications by Martin Kleppmann

• Grokking the System Design Interview (Educative)

• Google SRE Book for production-grade thinking

• YouTube mock interviews focused on L4-L5 System Design

How to handle a design prompt under pressure#

If a System Design question surprises you in the interview, here’s how to stay calm and structured:

1. Clarify requirements: Ask questions to scope the problem—what traffic, features, and constraints matter most?

2. Outline high-level components: Think APIs, databases, queues, and caching layers.

3. Talk through trade-offs: Don't aim for a perfect solution—aim to justify your reasoning.

4. Ask for feedback: Show you're collaborative and open to feedback.

Even a basic approach with clear reasoning often scores higher than an incomplete attempt at something complex.

What interviewers care about most in L4 design discussions#

For an L4-level System Design discussion, interviewers are primarily evaluating:

• Your ability to break down a problem 

• Your comfort with scale and latency trade-offs

• Your communication and collaboration skills

It’s less about architecture mastery and more about clear thinking, sound reasoning, and a willingness to ask the right questions.

How to incorporate System Design into your DSA prep#

If you're spending most of your time on LeetCode or other algorithmic problems, you can still sprinkle in System Design prep:

• Pair one design prompt with every 5–10 coding problems

• Reflect on how algorithms like caching, hashing, or graph traversal appear in systems

• Go through a System Design mock interview once a week to build familiarity

This keeps System Design in your muscle memory—without derailing your DSA momentum.

Why lightweight System Design is a strong L4 signal#

Even if System Design isn’t required, being able to talk through high-level architecture shows maturity. It signals:

• You think about scale and trade-offs, not just code

• You’re comfortable in ambiguous discussions

• You have the potential to grow into L5

It’s not about being perfect—it’s about showing thoughtfulness and readiness to take on more responsibility over time.

Should you focus on System Design for L4 interviews?#

For most L4 candidates, the priority is mastering algorithms and coding under pressure. But if you're targeting a backend or infra-heavy team, preparing lightweight System Design discussions is worth your time. At minimum, it shows you think like an engineer, not just a coder.

When in doubt, ask your recruiter. A 30-second question could save you hours of misaligned prep.

Final thoughts#

So, does Google ask System Design questions for L4? Sometimes. It depends on your team, role, and resume. But even if it's not a core focus, knowing how to design a basic, scalable system is a powerful signal.

If you're already investing in DSA prep, consider carving out a few sessions for System Design fundamentals. That extra effort might just be the signal that nudges you toward a hire.