System design guide
The Amazon system design interview: format, Leadership Principles and prep
Amazon's design round looks like any other on the surface, but it's scored alongside Leadership Principles and often framed around business constraints like cost and peak events. Here's what candidates report and how to prepare for it.
Amazon's loop structure is described here from public candidate reports and prep guides (sources at the end), not official Amazon material. It varies by team and level; confirm details with your recruiter.
Where design sits in the loop
- SDE II (L5): candidates commonly report a loop of four or five interviews, with at least one system design round, several coding rounds, and Leadership Principle questions in every round.
- Senior (L6) and above: more design weight, often more than one design-flavoured conversation, and more scrutiny of scope, operational ownership, and trade-offs.
- Bar Raiser: one interviewer from outside the hiring team, trained to hold the hiring bar consistent across teams. Their round may be behavioural, technical, or both.
- Track differences: some guides describe product-focused roles getting a design round with more emphasis on user experience and APIs, similar to Meta's product architecture round.
How Leadership Principles show up in design
Each interviewer is typically assigned a few Leadership Principles to assess, and in design rounds they're visible in how you reason:
| Principle | What it looks like in a design answer |
|---|---|
| Customer Obsession | Requirements framed around what the customer experiences (latency, never losing an order) |
| Frugality | Cost-aware choices: storage tiers, avoiding over-provisioning, managed services where they're cheaper to run |
| Dive Deep | Going below the boxes: data model, failure modes, what happens during a deploy |
| Bias for Action / Think Big | A simple version that ships, plus a clear path to scale |
| Ownership | Monitoring, alarms, on-call concerns, operational runbooks |
Expect a behavioural question or two in the same session, often about a system you built: be ready with a story about a design decision you made and what you'd change.
Typical prompts and framing
Candidates report e-commerce and infrastructure-flavoured prompts: a notification system, order or inventory services, a top-selling products / top-K service, a distributed cache, a rate limiter, or a payment flow. A recurring twist is a peak event: "now it's a major sale day with 10× traffic". Have an answer for burst capacity, back-pressure, and graceful degradation.
What strong answers include
- Clear requirements and an explicit statement of what's out of scope.
- Estimates for normal and peak load, with the peak driving capacity.
- Decoupling with queues where work can be asynchronous (order placed now, email sent later).
- Failure handling: retries with idempotency, dead-letter queues, what happens if a dependency is down.
- Operational thinking: metrics, alarms, deployment safety, cost.
- Trade-offs stated as decisions ("I'm choosing eventual consistency for inventory display but a conditional write for the reservation").
Example: the first 15 minutes of "design order notifications for a sale day"
- Scope (3–5 min). Channels (email, push, SMS), which events (order placed, shipped, delivered), and the customer promise: order confirmations within a minute, even at peak.
- Estimates (3 min). Normal and peak volume, with the sale-day peak (say 10×) driving capacity, plus SMS cost as a frugality point.
- Diagram (5–7 min). Order service publishes events; a notification service checks preferences and de-duplicates; per-channel queues and workers call providers.
- Deep dive and LPs. Priority isolation so marketing never delays confirmations (Customer Obsession), retries with idempotency (Dive Deep), alarms on queue age (Ownership).
The full design is in design a notification system.
Prep plan
- Use one structure for every answer: the 45-minute framework.
- Practise three or four e-commerce-style designs end to end, each with a "peak day" follow-up.
- Prepare two or three stories about systems you designed, mapped to Leadership Principles.
- Review consistency and caching trade-offs; inventory and checkout questions lean on both.
Sources
- Exponent, "Amazon system design interview": tryexponent.com/blog/amazon-system-design-interview
- Hello Interview, Amazon L5 guide: hellointerview.com/guides/amazon/l5
- Formation, "How to prepare for an SDE2 interview at Amazon": formation.dev
- IGotAnOffer, Amazon SDE interview: igotanoffer.com
FAQ
Does Amazon ask system design for SDE I?
Usually not as a dedicated round; SDE I loops focus on coding and Leadership Principles, though some include object-oriented or light design questions. For SDE II and above, at least one design round is standard.
High-level design or low-level design at Amazon?
Both appear. Candidates report high-level distributed-system design for most SDE II and senior loops, and object-oriented low-level design (classes and interfaces) in some loops. Ask your recruiter which to expect.
Should I use AWS services in my design?
Using AWS services as building blocks is natural at Amazon, but explain the property you need from each (durable queue, key-value store with single-digit-millisecond reads) and be ready to discuss how it works underneath and what it costs.