Company process / software engineering
Amazon SDE II interviews: assessment, design, coding and the loop
A preparation route for Amazon's published SDE II assessment and interview loop, with original exercises for code, system design and evidence-based behavioral answers.
- Assessment
- Coding, design, work style
- Loop
- Technical + behavioral
- Code
- Runnable and tested
Preparation map
Four moves before the interview
- 1
Read the invitation
Confirm whether the SDE II online assessment applies to your requisition.
- 2
Practice coding
Implement robust code with explicit edge-case tests and complexity analysis.
- 3
Practice design
Clarify requirements, then defend reliability and scaling choices.
- 4
Prepare stories
Connect concrete actions and results to the relevant Leadership Principles.
01 / FIELD NOTES
Understand the published SDE II path
Amazon's SDE II preparation materials currently describe an online assessment followed by an interview loop. Treat the recruiter invitation as the final authority for your specific process.
- The SDE II online assessment preparation page describes coding, system design and work-style sections. Its coding challenge is timed; plan setup and interruption-free time before opening the assessment.
- The SDE II interview-prep page describes a loop of four conversations. The interviewers assess technical competencies and nontechnical evidence connected with Leadership Principles.
- Amazon says to write syntactically correct code, not pseudocode. It calls out scalable, robust and well-tested solutions, including edge cases and invalid inputs.
- For system design, Amazon says to expect at least one software-systems question in the SDE II loop. The interview tests practicality, accuracy, efficiency, reliability, optimization and scalability.
02 / FIELD NOTES
Prepare for the online assessment
- Before the timed coding section, practice in the assessment environment or a similar plain editor. A familiar language with predictable standard-library behavior is usually safer than a trendy one you rarely use.
- For each problem, write one sentence about constraints, a small example, a brute-force baseline and the invariant behind your improved solution. Budget time for execution and corrections.
- For a short design scenario, identify the primary use case, data ownership, failure behavior and one scaling pressure. Clear, bounded trade-offs beat a list of every cloud service you know.
- Work-style questions are about how you actually work. Prepare honest examples of ownership, disagreement, customer impact and learning rather than reverse-engineering a preferred personality.
03 / FIELD NOTES
Connect technical and behavioral evidence
- Prepare several distinct STAR-style stories; reusing the same incident for every principle makes it harder to show breadth. Record your action, alternatives, measurable result and what you learned.
- A strong design answer states assumptions, sketches an initial architecture, probes failure and cost, then revises one choice based on an interviewer challenge.
- During coding, explain why a data structure fits the input scale, implement it, then run cases for boundaries, duplicates and unexpected input. Report unfinished work honestly.
- Ask the recruiter which round owns which competency. The published prep material provides a guide, while your schedule and role determine your actual loop.
04 / FIELD NOTES
Use a repeatable review sheet
- After each mock problem, mark whether the failure was requirement reading, algorithm choice, implementation, testing or communication. Practice the failing stage specifically.
- For each design mock, record the first requirement you forgot, the most important trade-off and a test or metric that would falsify your assumption.
- For each behavioral answer, delete vague team language until your personal contribution is visible, then add the business or customer result and a real reflection.
Original practice bank
Three tasks to work through aloud
These are ApplyDjinn practice prompts, not questions obtained from an employer. Use them to rehearse the reasoning and verification expected for the role.
Exercise 1
Coding: order deduplication
Prompt: Given payment events with an order ID, event time and status, return one final state per order even if events arrive duplicated and out of order.
Approach: Define tie-breaking rules and whether events are mutable, then use a map keyed by order ID. Update only when a newer event wins; distinguish idempotency from simply dropping repeated rows.
Test: Test duplicate IDs, same timestamp with conflicting status, empty input and malformed events.
Follow-up: How would you preserve correctness when events arrive across multiple workers?
Exercise 2
Design: inventory reservation
Prompt: Design a reservation service that prevents overselling while accepting bursts of orders.
Approach: Clarify reservation expiry and acceptable consistency. Identify a source of truth, atomic decrement or conditional write, idempotent request key, expiry worker and recovery path.
Test: Walk through concurrent buyers for the last item, request retries and worker failure after a reservation succeeds.
Follow-up: How would you keep browse availability responsive without treating the cache as authoritative?
Exercise 3
Behavior: difficult trade-off
Prompt: Tell a story where you chose a safer, slower launch over a higher-impact immediate release.
Approach: State the customer risk, evidence available, options considered, your own decision and the later outcome. Explain what you learned rather than claiming perfect foresight.
Test: Make sure the story shows both ownership and a concrete customer or operational result.
Follow-up: What data would have justified launching earlier?
Source check
Primary sources
Company process details come from these official pages. The exercises and preparation framework are original editorial material; confirm your own interview format with the recruiter.
- SDE II interview prep ↗Amazon Jobs
- SDE II online assessment prep ↗Amazon Jobs
- Software development interview topics ↗Amazon Jobs
Continue preparing with evidence
Choose a current role, map its requirements to projects you can defend, then practice the round your recruiter actually scheduled.