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Amazon Software Engineer Interview Guide 2026

Complete Amazon Software Engineer interview guide. Learn about the interview process, question types, and preparation tips. Practice 238+ real interview ques...

Topics: Amazon, Software Engineer, interview guide, interview preparation, Amazon interview

Author: PracHub

Published: 3/17/2026

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Amazon Software Engineer Interview Guide 2026

Complete Amazon Software Engineer interview guide. Learn about the interview process, question types, and preparation tips. Practice 238+ real interview ques...

6 min readUpdated Jun 15, 2026295+ practice questions
295+
Practice Questions
4
Rounds
8
Categories
6 min
Read
Contents
TL;DRSample QuestionsAbout the Interview ProcessWhat to expectThe interview processRound types in the loopCoding / algorithmsLow-level / object-oriented designSystem designBehavioral / Leadership PrinciplesBar RaiserWhat they testCoding and fundamentalsDesign judgmentLeadership PrinciplesHow to prepare and stand outFAQ
Practice Questions
295+ Amazon questions
Amazon Software Engineer Interview Guide 2026

TL;DR

Amazon's 2026 Software Engineer interview evaluates two things at once: technical execution and alignment with Amazon's Leadership Principles. Strong coding alone is rarely enough. Behavioral questions appear in nearly every stage, and interviewers tend to probe for metrics, tradeoffs, ownership, judgment, and your specific contribution rather than what your team did. The process is fairly standardized, though the exact shape depends on the level and team. Entry-level loops lean more heavily toward coding and behavioral evaluation, while experienced roles (SDE II and above) add more design depth. Many candidates begin with an online assessment that goes beyond pure coding before reaching the final loop.

Interview Rounds
HR ScreenOnsiteTake-home ProjectTechnical Screen
Key Topics
Behavioral & LeadershipCoding & AlgorithmsSoftware Engineering FundamentalsSystem DesignML System Design
Practice Bank

295+ questions

Estimated Timeline

2–4 weeks

Browse all Amazon questions

Sample Questions

295+ in practice bank
System Design
1.

Design streaming error-log counting with moving average

MediumSystem Design

Design a core component in a streaming system:

Input:

  • Multiple upstream services continuously emit log events.
  • Each event includes at least: service_id, timestamp, log_level, message.

Tasks:

  1. Filter and output only error logs.
  2. Maintain real-time per-service error count.
  3. Maintain a moving average of error count per service over a sliding time window.
  4. Trigger an alarm when a service’s error rate/moving average crosses a threshold.

Describe the architecture, state management, windowing approach, and how you handle late events, scale, and fault tolerance.

Solution
2.

Design delayed job scheduler (LLD)

HardSystem Design

Design a Delayed Job Scheduler (Low-Level Design)

Design a service that schedules a job to execute X seconds in the future with second-level accuracy. Produce a low-level design covering the public APIs, the in-memory and on-disk data structures, persistence, the execution model, and the operational concerns enumerated below.

This is an LLD prompt: the interviewer wants concrete APIs, data structures with their time/space complexity, a durable schema, an explicit state machine, an execution/lease protocol, and class responsibilities — not a boxes-and-arrows HLD diagram.

Constraints & Assumptions

  • Second-level precision is sufficient; sub-second (tens-of-ms) jitter is acceptable. The system should never fire a job early relative to its due time — lateness is the only acceptable error.
  • The system must survive process restarts and crashes without losing scheduled jobs: a schedule() call that returns success must be durable even if the process dies one millisecond later.
  • At-least-once delivery is acceptable by default; you should also discuss what it would take to move toward exactly-once.
  • Assume a target of up to roughly $10^6$–$10^7$ pending jobs with low-thousands schedule QPS, and that multiple scheduler instances run for high availability.
The combination of "$10^7$ pending jobs" + "must survive crashes" + "second-level accuracy" rules out both extremes. Pure in-memory loses jobs on crash; polling a database every second over millions of rows is too expensive for fine-grained accuracy. The interesting answers reconcile a **durable source of truth** with a **fast near-term firing mechanism**.

Clarifying Questions to Ask

Before designing, scope the problem with the interviewer:

  • What is the acceptable firing accuracy and is it one-sided (never early vs. bounded lateness)?
  • What delivery semantics are required — at-least-once, or must we attempt exactly-once?
  • How do jobs execute — an in-process handler, an HTTP callback, or a message onto a queue? Are handlers idempotent?
  • What is the expected scale: number of pending jobs, schedule QPS, and maximum delay horizon (seconds vs. months)?
  • Is this single-tenant or multi-tenant? Do we need per-tenant fairness and quotas?
  • What are the availability expectations (single node vs. HA across instances)?

What a Strong Answer Covers

The interviewer is looking for these dimensions (not the answers themselves — work them out in your design):

  • A clear source-of-truth vs. cache split and a justification for it.
  • A complete, well-justified public API with input validation and idempotent submission.
  • A durable schema with the right indexes and a precise account of when the client is acknowledged.
  • An explicit job state machine with named terminal states and how retries reuse the scheduling path.
  • A defensible data-structure choice with complexity, plus when you'd switch structures.
  • A safe-under-concurrency execution protocol (atomic claim / lease / ack) that is correct even during failover.
  • Correct timekeeping reasoning (wall-clock vs. monotonic) tied to which decision each clock governs.
  • Honest delivery-semantics trade-offs, including why true exactly-once is generally impossible.
  • Fairness, quotas, and backpressure across tenants.
  • A testing strategy that treats durability/recovery as a first-class tier, and observability/SLO signals.

What to cover

Part 1 — Public APIs

Define and justify the public interface, including at least:

  • schedule(job, delaySeconds) -> jobId
  • scheduleAt(job, epochMillis) -> jobId
  • cancel(jobId) -> success/failure
  • getStatus(jobId) -> job metadata
  • Optional: reschedule(jobId, newDelaySeconds)

Specify the options each call accepts, what getStatus returns, and how you validate inputs.

Think about a c
Solution
Coding & Algorithms
3.

Maximize weighted subsequence pairs with wildcards

MediumCoding & AlgorithmsCoding

You are given a string s of length n consisting only of characters '0', '1', and '!'. Each '!' can be replaced by either '0' or '1'.

For the final binary string, define:

  • count10 = number of index pairs (i, j) with i < j, s[i] = '1', s[j] = '0' (a subsequence pair, not necessarily adjacent).
  • count01 = number of index pairs (i, j) with i < j, s[i] = '0', s[j] = '1'.

Given integers x and y, the total “error” is:

error = x * count10 + y * count01.

Return the maximum possible error over all replacements of '!', modulo 1_000_000_007.

Example: s = "101!1" (with given x, y).

Solution
4.

Compute minimum passes to collect numbers

MediumCoding & AlgorithmsCoding
Question

You are given an array shelf of n distinct integers that is a permutation of 1…n. Starting with target = 1, you repeatedly scan shelf from left to right:

While scanning, if the current element equals target, you collect it and immediately increment target (target += 1).

You never move left during a scan. When you reach the end of the array, if target ≤ n, you start a new full left-to-right pass and continue looking for the current target.

Return the minimum number of full passes required to collect all numbers 1…n.

Example: shelf = [3,1,5,4,2] → 3 passes (collect 1,2 in pass 1; 3,4 in pass 2; 5 in pass 3).

Design an O(n) algorithm and implement it.

Solution
Behavioral & Leadership
5.

Evaluate actions in Amazon simulation

HardBehavioral & Leadership

Amazon Work Simulation: Purpose, Modules, and Design Decisions

Context and Assumptions

The Work Simulation is a timed, scenario-based assessment used in a software engineering hiring process. It blends situational judgment, product sense, and system design trade-offs. Because the original prompt references choices without listing them, this version includes concise, realistic options so the task is fully self-contained. Use the 1–5 effectiveness scale below when asked to rate options:

  • 5 = Most effective
  • 4 = Effective
  • 3 = Mixed/acceptable
  • 2 = Ineffective
  • 1 = Harmful

Tasks

  1. Purpose and Structure
  • Explain the purpose of the Amazon Work Simulation and outline a plausible five-module structure relevant to a software engineer role.
  1. Workplace Judgment (Situational Scenarios)
  • Scenario: You discover late in the sprint that a critical dependency owned by another team will slip by two weeks, jeopardizing your committed release. Which actions are most effective? Rate each on the 1–5 scale and briefly justify. a) Quietly work overtime to try to hide the impact and maintain the original date. b) Immediately inform your manager and the PM with impact, options (de-scope, feature flag, phased rollout), and a revised plan. c) Escalate to the other team’s director, cc-ing senior leadership, requesting they re-prioritize to meet your date. d) Proactively implement a feature-flagged fallback and update stakeholders on a new date with clear trade-offs. e) Reprioritize your team’s backlog to pull forward unrelated high-impact items while the dependency lands.
  1. Real-Time Voting (Voice Service) — Vote Storage Strategy
  • Choose the most effective strategy and briefly justify. a) Single-AZ relational DB (RDS) table; one row per vote; synchronous writes. b) Redis cluster incrementing per-item counters; periodic batch writes to durable storage. c) Append-only event stream (e.g., Kinesis/Kafka) for all votes; serverless/stream processors aggregate to DynamoDB counters with idempotency and TTL for raw votes. d) Direct writes to S3 objects (one object per vote) with later batch aggregation.
  1. SaaS Inventory Management — Next Design Actions from Emails
  • You receive these emails:
    • Sales: “Pilot customers need multi-tenant support next month.”
    • Support: “Image uploads are slow; customers report timeouts during peak hours.”
    • Compliance: “We need immutable audit logs of inventory adjustments for 7 years.”
  • From the candidate actions below, choose the best next three actions to start this week. a) Define and implement a tenant isolation model (tenant_id everywhere; per-tenant rate limits; secrets isolation). b) Buy more compute for the upload service; revisit architecture later. c) Introduce presigned URLs to S3 + CDN for uploads; async thumbnailing; backpressure on API. d) Create a product roadmap slide deck; schedule stakeholder review next month. e) Implement immutable, append-only audit logging (WORM storage or tamper-evident logs) with schema and retention.
  1. Thumbnail Storage Options — Compare and Rate
  • Rate each option (1–5) for scalability, cost, latency, complexity, and give an overall rating. a) Store thumbnails as BLOBs in a relational DB. b) Store images in S3; serve via CDN; DB stores object keys/URLs. c) Generate thumbnails on-the-fly with Lambda@Edge; cache at CDN; store originals in S3. d) Store images on an NFS/EFS mount shared by web servers.
  1. Traffic-Video Service (Queued Ingestion) — Message Format Priorities
  • Prioritize the following design actions for a robust message format: a) Use a binary serialization format with an explicit schema (e.g., Protocol Buffers or Avro). b) Include an envelope with message_id, schema_version, timestamp, payload_type, and checksum. c) Define backward/forward compatibility rules (reserved fields, optional fields, deprecation policy). d) Add compression and encryption-at-rest/in-flight; document cipher and key rotation
Solution
6.

Describe Deadline, Mistake, Problem-Solving, and AI Experiences

MediumBehavioral & Leadership

You are interviewing for a Software Engineer (Intern) role at Amazon, in a back-to-back loop of two 60-minute rounds. Each round mixes a behavioral block with a coding problem; the prompts below are the behavioral portion (one round was with a peer engineer, the other with the hiring manager).

Answer each prompt using a clear, concrete example from your past work, projects, internships, research, or coursework — one story per prompt, with your personal contribution front and center. Amazon explicitly scores behavioral answers against its Leadership Principles (e.g., Ownership, Bias for Action, Earn Trust, Dive Deep, Deliver Results, Learn and Be Curious, Are Right, A Lot), so each story should surface evidence for the principle its prompt is testing.


Part 1 — A tight deadline

Tell me about a time you faced a tight deadline. What was at stake, how did you decide what to do, and what was the outcome?

Use a structured narrative (Situation → Task → Action → Result). The signal lives in the **Action**: what you cut, parallelized, or escalated — not that you "worked hard."
Show a deliberate **tradeoff under constraint** — scope reduction, prioritization, surfacing risk early — rather than heroics. Tie it to *Bias for Action* and *Deliver Results*.

Part 2 — A mistake you made

Tell me about a time you made a mistake. How did you discover it, what did you do about it, and what changed afterward?

Choose a **real** mistake with genuine consequence that you **owned** — not a disguised humble-brag ("I care too much"), and not someone else's fault. Accountability is the point.
The recovery and a **systemic prevention** (a test, a check, monitoring, a process change) matter more than the slip itself. This maps to *Earn Trust* and *Ownership*.

Part 3 — A difficult problem you solved

Tell me about a time you solved a difficult problem. Explain how you discovered the problem, how you developed a solution, and how you drove it to completion.

The prompt explicitly asks for discovery → solution → completion. Map your story to all three: how you *noticed* it (a metric, a bug report, a failing test), how you *chose* among alternatives, and how you *shipped and verified* the fix.
This is where *Dive Deep* and *Are Right, A Lot* are scored. Name the hypotheses you tested and the evidence that confirmed the root cause — not just the final fix.

Part 4 — Using generative AI tools

Tell me about your experience using generative AI tools. Describe how you used them responsibly and what impact they had.

Position AI as an **assistant under your judgment**, not a replacement for it. Concretely: how did you *verify* the output (tests, review, reasoning) before trusting it?
Name the real risks you managed — hallucinations, secret/confidential-data leakage, security, licensing — and how your usage respected them. This maps to *Learn and Be Curious* plus good judgment.

Constraints & Assumptions

  • This is an early-career / intern loop: interviewers expect honest examples from school, internships, side projects, research, or hackathons — not necessarily large production systems.
  • Format: two back-to-back 60-minute rounds; budget each behavioral answer to roughly 2–4 minutes spoken, leaving room for follow-up drilling and the coding question in the same round.
  • Amazon expects specifics and metrics. Vague stories ("we worked hard and shipped it") fail; concrete tools, constraints, tradeoffs, and numbers pass.
  • Assume the interviewer will interrupt with "what was your part?" and "what did the data show?" — your story must survive that probing, so it should be true and your own.

Clarifying Questions to Ask

For a "tell m

Solution
Software Engineering Fundamentals
7.

Validate AI-Generated Code Safely

MediumSoftware Engineering Fundamentals

Generative AI coding tools are now part of many teams' day-to-day workflow, and interviewers increasingly want to know not just whether you use them, but how you keep their output trustworthy. This is an open-ended, experience-driven question: there is no single correct answer, but a strong response demonstrates disciplined engineering judgment.

Walk the interviewer through your hands-on experience with generative AI tools for software development, and then explain the concrete process you use to ensure that AI-generated code is correct, maintainable, and safe to merge. Your answer should address testing, code review, debugging, and the limits you would place on using generated code in production systems.

Part 1 — Your Experience with Generative AI Tools

Describe how you have actually used generative AI in your development workflow. Be specific about the kinds of tasks you delegate to it, where it has helped, and where it has fallen short or required correction.

Ground the answer in **concrete tasks** rather than generalities — name the situations where you reach for the tool (e.g. boilerplate, drafting tests, exploring an unfamiliar API, scaffolding a well-scoped function) versus where you deliberately do not.

Part 2 — Ensuring Correctness, Maintainability, and Safety

Explain the end-to-end process you follow before AI-generated code is allowed into the codebase. Treat this as the heart of the question: the interviewer is probing your engineering discipline, not your enthusiasm for the tool.

It helps to anchor your process in a single guiding analogy about how much trust generated code earns before it can merge. Pick one that forces the code to clear the same bar as any other contribution, and let that analogy organize the rest of your answer.
Make sure each of the four named dimensions appears: **testing**, **code review**, **debugging**, and **limits**. For each, say something concrete about *how* you apply it to generated code specifically, rather than naming the activity and moving on.
Strong answers go past "does it work" to the **security/privacy** dimension and the **automated CI** dimension, and they close on who is **accountable** for merged code. You don't need to recite every check — show the interviewer you know these categories exist and treat them as non-negotiable.

Constraints & Assumptions

  • This is a behavioral / open-ended discussion question, not a coding exercise. There is no boilerplate to write; the interviewer is evaluating how you reason, not a passing test suite.
  • Assume the context is a production system at a large company (e.g. Amazon), so internal policy, compliance, and safety considerations are in scope.
  • A complete answer is concrete and personal — drawn from real experience — rather than a generic list of best practices.

Clarifying Questions to Ask

  • What kind of system is the code destined for — a prototype, internal tooling, or a customer-facing / safety-critical production service? (This changes how conservative you should be.)
  • Are there company policies governing what may be shared with external AI tools (proprietary code, customer data, secrets)?
  • What does the team's existing quality bar look like — required code review, CI gates, test-coverage expectations?
  • Is the interviewer more interested in my personal workflow or in how I would set team-level policy for AI-assisted development?

What a Strong Answer Covers

The interviewer is listening for the following signals (this is a checklist of dimensions, not the answers themselves):

  • Concrete experience: specific tasks delegated to AI, with honest examples of both successes and failures.
  • A "trust but verify" stance: AI as a productivity tool, never an authority.
  • Comprehension before merge: the candidate insists on being
Solution
8.

Debug Watch List Movie Operations

MediumSoftware Engineering Fundamentals

You are given a full-stack Movie DB application. Users can log in, create, update, and delete watch lists, and add or remove movies from a watch list.

Several unit tests are failing around watch-list movie operations. Your job is to debug and fix the backend logic so that all of the listed scenarios behave correctly, with the right persistence and the right HTTP responses. This is a debugging exercise: the data model and routing already exist — focus on correcting the handler logic rather than redesigning the system.

The following scenarios must work correctly:

  1. Add a movie to an existing watch list.
  2. Add a movie that is already present in the watch list.
  3. Remove a movie from an existing watch list.
  4. Add many movies to a watch list, then remove them one by one.
  5. Try to add a movie to a watch list that does not exist.
  6. Try to remove a movie from a watch list that does not exist.

Constraints & Assumptions

Assume a conventional REST contract such as:

  • POST /watchlists/{watchListId}/movies adds a movie (the movie identifier comes from the request body).
  • DELETE /watchlists/{watchListId}/movies/{movieId} removes a movie.
  • 404 Not Found is returned when the watch list or movie does not exist.
  • 409 Conflict is returned when attempting to add a duplicate movie.
  • 201 Created or 200 OK is returned for a successful add.
  • 200 OK or 204 No Content is returned for a successful delete, depending on the existing API convention.

Additional working assumptions:

  • The watch list stores a collection of movie identifiers, and identifiers may be object/reference types rather than plain strings.
  • The persistence layer is asynchronous (handlers must wait for a save to complete before responding).
  • Where the contract above leaves a choice (e.g. 201 vs 200, 200 vs 204), match whatever the existing passing tests and surrounding code already assume — do not introduce a new convention.

Clarifying Questions to Ask

  • Are movie identifiers stored as plain strings or as object/reference IDs, and how should two identifiers be compared for equality?
  • For a successful add, do the tests expect 201 Created or 200 OK, and for a successful delete do they expect 200 OK or 204 No Content?
  • When adding a movie, must the movie itself exist in the database, or is it enough that the identifier is well-formed?
  • When the watch list exists but the movie is not currently in it, what status should a delete return — 404, or a no-op success?
  • Is the persistence layer synchronous or asynchronous, and are partial/in-memory mutations automatically saved?
  • Should any of these operations be idempotent (e.g. deleting a movie that isn't present), or should they error?

What a Strong Answer Covers

The interviewer is looking for these signals — not just a passing test count:

  • A clear read → validate → mutate → persist → respond ordering in each handler.
  • Correct existence checks for both the watch list and (on add) the movie, before any mutation.
  • Correct duplicate detection that compares identifiers by value rather than by reference.
  • Guaranteeing the mutation is persisted before the response is sent.
  • Status-code discipline: each failure path maps to the status the contract/tests expect, and each success path uses the agreed code.
  • Control-flow correctness: every error branch stops execution (no falling through to a second response) and every async call is awaited.
  • A debugging method: the candidate reasons about why a given test fails (null object, unsaved mutation, reference comparison, missing return) rather than guessing.
  • Awareness that not all six tests may need to pass to advance, but that the fixes should be principled, not hacks targeting a single assertion.

Part 1 — Add a movie (scenarios 1, 2, 5)

Make the add handler satisfy scenarios 1, 2, and 5. Decide which conditions must be validated before anything is added, which status each failure map

Solution
ML System Design
9.

Design an email spam detection system

HardML System Design

System Design: End-to-End Email Spam Detection

Context

Design an end-to-end system that detects and handles spam emails at scale. Assume you are building for a large consumer email service handling high throughput and strict latency requirements. The design should cover data, ML, serving, experimentation, and operations.

Requirements

  1. Problem Definition and Labeling
    • Define the objective(s) and action outcomes (e.g., block, quarantine, inbox with banner).
    • Labeling sources and policies.
  2. Data Sources and Collection
    • Inbound traffic, user reports, honeypots, abuse teams, reputation feeds.
    • Collection, sampling, retention, and governance.
  3. Feature Engineering
    • Content features (text, URLs, attachments), headers, sender/domain/IP reputation, network/behavioral signals.
  4. Model Choices and Training
    • Baseline rules, supervised ML models, online learning.
    • Handling class imbalance, feature hashing, model calibration.
  5. Serving Architecture and Constraints
    • Placement in the mail pipeline, APIs, latency/throughput targets, caching, fallbacks.
  6. Thresholding and Calibration
    • Score-to-action mapping, per-segment thresholds, calibration methods.
  7. Evaluation Metrics
    • Precision, recall, ROC/PR analysis, and cost-weighted metrics.
  8. Abuse/Adversarial Defenses and Feedback Loops
    • Evasion tactics, spoofing defenses, URL/attachment handling, user feedback integration.
  9. Cold Start, Concept Drift, Retraining Cadence
    • New senders/domains, seasonal drift, automated retraining.
  10. Online Experimentation
    • A/B testing, ramp strategies, guardrails.
  11. Monitoring, Logging, Rollback
    • Real-time and batch monitoring, alerting, safe rollback.
  12. Privacy and Compliance
    • Data minimization, encryption, regional residency, user controls.
Solution
10.

Design a fraud detection system

HardML System Design

System Design: Real-Time Payment Fraud Detection

Context

Design a real-time fraud detection system for online payments (card-not-present). The system must score each transaction during authorization and decide whether to approve, decline, or route to manual review within a tight latency budget.

Assume:

  • End-to-end p95 decision latency budget: 100 ms (from feature retrieval to decision), with soft degradations permitted.
  • Labels (e.g., chargebacks) arrive with delays (weeks). You must train with delayed/noisy labels and operate with streaming features.

Requirements

Discuss and propose designs for:

  1. Events and Labels
  • What events to ingest (e.g., authorizations, captures, refunds, chargebacks, disputes, user actions).
  • How to define positive/negative labels (chargebacks, disputes) and handle label delay.
  1. Feature Store
  • Feature categories (user, device, merchant, payment instrument, velocity, graph/network features).
  • Offline vs. online stores, consistency, TTL, backfilling, and time-travel for training.
  1. Model Selection
  • Compare tree ensembles, deep models (e.g., sequence or representation models), and anomaly detection for cold start.
  • Calibration, class imbalance handling, and cost-sensitive learning.
  1. Rule Engine + Model Ensemble
  • Combining deterministic rules with ML scores, ensembling strategies, and reason codes.
  1. Data Pipeline and Streaming Inference
  • Ingestion, stream processing, feature computation, online retrieval, and a low-latency inference service.
  1. Latency Budgets and Fallbacks
  • Budget breakdown, caching, degradation paths (e.g., rules-only), and idempotency.
  1. Thresholding and Trade-offs
  • How to set thresholds to balance false positives vs. fraud loss; expected value formulation.
  1. Human-in-the-Loop Review
  • Review queue design, sampling strategies, SLAs, active learning, and feedback loops.
  1. Concept Drift and Adversarial Adaptation
  • Continuous training, drift detection, canaries, and defenses.
  1. Explainability Requirements
  • Feature attributions, rule traces, and audit logging.
  1. Online Experiments
  • A/B/shadow testing, guardrail metrics, ramp policy, and bias control.
  1. Monitoring and Alerting
  • Precision at top-K, approval rate, fraud rate, latency SLOs, data quality, and feature drift.
  1. Incident Response and Rollback
  • Kill switches, model/version rollback, runbooks, and postmortems.
Solution
Machine Learning
11.

Explain core ML fundamentals

MediumMachine Learning

Machine Learning Fundamentals: Regularization, Losses, PCA, and Random Forests

Assume standard supervised learning with linear models for regression/classification, PCA for dimensionality reduction, and Random Forests for tabular data. Answer the following:

1) L1 vs. L2 Regularization

Compare L1 (Lasso) and L2 (Ridge) regularization in terms of:

  • Sparsity of learned coefficients
  • Optimization geometry and differentiability
  • Robustness to outliers (clarify what kind of outliers and how the penalty interacts with the loss)

2) Choosing Loss Functions and Gradient Properties

Explain how to choose loss functions for:

  • Regression: MSE vs. MAE (and mention Huber if relevant)
  • Classification: logistic/cross-entropy (and note hinge/focal if relevant) Discuss their gradient properties, optimization behavior, and sensitivity to outliers.

3) PCA

Describe PCA’s objective (variance maximization vs. reconstruction error minimization), the fitting and transform steps, and how to select the number of components.

4) Random Forests

Explain how Random Forests are trained, their bias–variance trade-off, the limits of impurity-based feature importance, and key hyperparameters (with brief tuning guidance).

Solution
12.

Explain overfitting, regularization, and LLM techniques

MediumMachine Learning

You’re in an ML interview. Answer the following conceptual questions clearly and concisely, using examples where helpful:

1) Model fit

  • What is overfitting vs underfitting?
  • For each, list common symptoms you would see in training/validation curves.
  • Give 3–5 practical ways to mitigate each problem.

2) Regularization

  • Compare L1 vs L2 regularization:
    • objective/penalty form
    • effect on weights (sparsity vs shrinkage)
    • when you would prefer one over the other
    • interaction with correlated features

3) LLM-related topics

Explain the purpose, core idea, and major trade-offs for:

  • LoRA (low-rank adaptation) for fine-tuning
  • RAG (retrieval-augmented generation)
  • Agents (tool-use / planning loops)

For each, describe:

  • what problem it solves
  • what data it needs
  • what can go wrong (failure modes)
  • how you would evaluate it in production

4) Project deep dive (CV example)

Pick one computer-vision project you’ve worked on (e.g., classification/detection/segmentation) and be prepared to explain:

  • problem statement and business goal
  • dataset construction/labeling and leakage risks
  • model choice and baseline
  • training details (augmentation, loss, class imbalance, hyperparameters)
  • evaluation metrics and thresholding
  • key errors you found and how you fixed them
  • how you would deploy/monitor it (latency, drift, feedback loop)
Solution
Data Manipulation (SQL/Python)
13.

Compute unique visitors per department from clicks

MediumData Manipulation (SQL/Python)

Given tables Products(product_id, department, category, subcategory) where department > category > subcategory form a hierarchy, and ClickLog(user_id, product_id, event_ts) that records user clicks, write SQL to compute the number of unique customers who visited (clicked any product in) a specified department over a given time range. Ensure correct mapping from product_id to its department and avoid double-counting users who clicked multiple products/categories within the same department. Explain your indexing/partitioning strategy for large-scale data and how you would extend the query to return results for all departments.

Solution
14.

Manipulate time-series with Pandas groupby

MediumData Manipulation (SQL/Python)Coding

Given a DataFrame events(user_id, event_type, ts_utc, revenue):

  1. Parse ts_utc as timezone-aware, convert to America/Los_Angeles, and handle DST transitions.
  2. Compute daily active users (DAU) and a 7-day moving average.
  3. For each user and event_type, compute a 7-day rolling count.
  4. Produce weekly retention: the number and rate of users active in week w who return in week w+1.
  5. Resample to fill missing calendar dates with zeros. Provide idiomatic, vectorized Pandas code (no explicit Python loops).
Solution
Analytics & Experimentation
15.

Brainstorm a business problem approach

MediumAnalytics & Experimentation

Analytics & Experimentation Brainstorm (Scenario Provided)

Context

You are evaluating a feature proposal for a large consumer e-commerce site: add a "sticky Add to Cart" (ATC) button on mobile product detail pages (PDPs) that stays visible as users scroll. The goal is to increase add-to-cart conversion without harming performance, accessibility, or overall customer experience.

Assume for planning purposes:

  • Baseline PDP add-to-cart rate (per eligible session) = 8%.
  • Daily eligible mobile PDP sessions = 80,000.
  • Significance level α = 0.05 (two-tailed), power = 0.8.
  • Desired minimum detectable effect (MDE) = 5% relative uplift on ATC rate.

Task

Brainstorm and outline an approach that covers:

  1. Success metrics and constraints
  • Define primary/secondary metrics and guardrails. State key non-functional constraints (e.g., latency, accessibility).
  1. Hypotheses
  • List plausible hypotheses for why the feature may help or harm, and where effects might differ (segments, categories, device characteristics).
  1. Required data and instrumentation
  • Identify what data needs to be logged (events, identifiers, attributes), experiment keys, and quality checks.
  1. MVP experiment or analysis plan
  • Define randomization unit and eligibility.
  • Specify control/variant and exposure.
  • Estimate sample size and recommend test duration.
  • Outline analysis steps and decision criteria.
  1. ML versus heuristic baselines
  • If you were to gate or personalize the feature, compare a simple heuristic baseline with a potential ML approach and how you would evaluate them.
  1. Risks and mitigations
  • Enumerate major product, data, and statistical risks and how you would detect and mitigate them.
Solution

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About the Interview Process

What to expect

Amazon's 2026 Software Engineer interview evaluates two things at once: technical execution and alignment with Amazon's Leadership Principles. Strong coding alone is rarely enough. Behavioral questions appear in nearly every stage, and interviewers tend to probe for metrics, tradeoffs, ownership, judgment, and your specific contribution rather than what your team did.

The process is fairly standardized, though the exact shape depends on the level and team. Entry-level loops lean more heavily toward coding and behavioral evaluation, while experienced roles (SDE II and above) add more design depth. Many candidates begin with an online assessment that goes beyond pure coding before reaching the final loop.

The interview process

The journey from application to decision typically moves through these stages:

  1. Resume screen — A recruiter and hiring team review your background for level fit, relevant technical stack, domain relevance, and evidence of impact. Make scope, ownership, and outcomes obvious; this is what determines whether you advance.
  2. Online assessment (OA) — For many roles the OA is the first real screen. It commonly includes one to two coding problems and often adds work-style/work-simulation questions; some assessments include a lightweight system-thinking component. It evaluates coding correctness and efficiency alongside how well your working style fits Amazon.
  3. Recruiter or phone screen — Usually a 30–60 minute call covering your resume, past projects, motivation, and Leadership Principles examples. Some candidates also get a coding problem or technical discussion. This checks role fit, communication, and baseline technical depth.
  4. Final loop — Typically 3–5 interviews of ~45–60 minutes each, usually as a virtual onsite. The loop is a mix of round types (described below), and behavioral questions are embedded throughout rather than confined to one round.
  5. Debrief and decision — The panel meets to compare evidence, weigh strengths and concerns, and decide on outcome and level. Results are often communicated within a few business days, though scheduling can stretch the overall timeline. Outcomes can include an offer, a different level than you applied for, team matching, a hold, or a rejection.

Treat timelines and exact round counts as typical rather than guaranteed — they vary by team, level, and location.

Round types in the loop

The final loop draws from the following interview types. Not every loop includes all of them, and several skills are often tested within a single round.

Coding / algorithms

A live coding round focused on data structures, algorithms, clean implementation, debugging, and complexity analysis. Expect medium-to-hard problems involving trees, graphs, hashing, recursion, heaps, dynamic programming, and traversal. Interviewers watch how you clarify requirements, handle edge cases, and explain tradeoffs — not just whether you reach a correct answer.

Low-level / object-oriented design

This round pairs implementation with design thinking. You may be asked to model a small class hierarchy, API, or subsystem, then implement or extend part of it while discussing abstractions, maintainability, testing, and edge cases. The goal is code that is both correct and extensible, with production-minded judgment.

System design

Most common for experienced hires (SDE II and above). You'll typically design a scalable service or feature and discuss architecture, throughput, latency, reliability, data modeling, caching, consistency, and failure handling. Interviewers care less about memorized buzzwords and more about whether you make sensible tradeoffs under realistic constraints.

Behavioral / Leadership Principles

Behavioral evaluation runs across the whole loop, and one round is often weighted toward it. Expect multiple questions about ownership, customer focus, conflict, failure, disagreement, raising standards, and delivering under constraints. Amazon wants detailed stories with your specific actions, the reasoning behind them, and measurable outcomes.

Bar Raiser

The Bar Raiser is typically one of the loop interviews rather than a separate stage — a trained interviewer from outside the hiring team who assesses whether you meet or exceed Amazon's hiring bar. The conversation may be behavioral, technical, or mixed, but it usually goes deeper and probes harder than other rounds, with particular attention to judgment, standards, and consistency.

What they test

Coding and fundamentals

The core remains data structures, algorithms, and practical engineering judgment. Be ready for arrays, strings, hash maps, linked lists, stacks, queues, trees, graphs, recursion, backtracking, sorting, searching, greedy methods, heaps, and dynamic programming. Recognizing a pattern isn't enough — you need to write clean, executable code, reason about edge cases, and explain time and space complexity accurately.

Design judgment

Design rounds reward grounded engineering over textbook answers:

  • Low-level design: object-oriented modeling, abstraction, API choices, extensibility, testing strategy, refactoring, and implementation tradeoffs.
  • System design: service decomposition, scaling, availability, consistency, caching, sharding, load balancing, asynchronous processing, message queues, observability, and failure recovery.

In both, connect your choices back to customer needs and operational realities rather than reciting components.

Leadership Principles

Behavioral performance carries as much weight as technical skill. Amazon's principles that frequently surface include Customer Obsession, Ownership, Dive Deep, Have Backbone; Disagree and Commit, Insist on the Highest Standards, Deliver Results, Are Right, A Lot, and Frugality. Your stories should show concrete impact, sound judgment, willingness to challenge decisions respectfully, and the ability to learn from failure. Interviewers push for detail, so vague, team-attributed answers tend to underperform.

How to prepare and stand out

  • Prepare Leadership Principles stories as seriously as coding. Have specific examples ready for failure, conflict, ownership, customer impact, ambiguity, raising standards, and disagreeing with a manager or stakeholder.
  • Make every behavioral answer evidence-based. State the scope, your exact role, the alternatives you weighed, the tradeoff you chose, and the measurable result.
  • Clarify before you code. Ask about input assumptions, constraints, edge cases, expected scale, and error handling instead of jumping straight into implementation.
  • Write runnable code, not pseudocode. Amazon evaluates correctness and readability, so use clear naming, handle edge cases, and talk through tests as you go.
  • Treat the OA as broader than a coding screen. Prepare for coding and work-style components rather than assuming it's just algorithm questions.
  • Practice mixed rounds. Amazon commonly blends behavioral, coding, and design within a session; smooth transitions between storytelling and technical reasoning make you look interview-ready.
  • Prepare for follow-ups. Interviewers often ask why you chose a path, what failed, what you'd change now, and how you knew a decision was right — so your examples and designs need real depth.

Frequently Asked Questions

It is definitely tough, but not impossible if you prepare the right way. When I went through it, the hard part was not just coding difficulty. It was switching between data structures, system design for more senior roles, and behavioral questions tied to Amazon’s Leadership Principles. The coding questions were usually in the medium to hard range, but the pressure and follow-up questions made them feel harder. If you are solid with problem solving and can explain tradeoffs clearly, it feels demanding but fair.

The process usually starts with a recruiter screen, then an online assessment for many candidates. After that, there is often a phone or technical screen with coding and discussion. The final loop usually has several back-to-back interviews, often four or five, covering coding, problem solving, design, and behavioral questions. For more experienced engineers, system design shows up more heavily. One interviewer may act as the bar raiser. The exact order can vary by team, but that is the general shape I saw.

For most people, I would say give yourself six to ten weeks if you already know the basics, and longer if algorithms are rusty. I needed a few weeks just to get back into writing clean code under time pressure. A good plan is to practice coding problems most days, review core data structures, and spend separate time on Leadership Principles stories. If you are going for mid-level or senior roles, add regular system design practice too. Short, steady prep worked much better for me than cramming.

The biggest buckets are data structures and algorithms, coding fluency, and behavioral stories built around the Leadership Principles. I would focus most on arrays, strings, hash maps, trees, graphs, heaps, stacks, queues, recursion, dynamic programming, and graph traversal. You also need to talk through time and space complexity without sounding shaky. For experienced roles, system design matters a lot, especially APIs, scaling, storage choices, and tradeoffs. I also found debugging, edge cases, and writing clean readable code mattered more than trying to be flashy.

The biggest mistake I saw was treating Amazon like it was only a coding interview. People underestimate the behavioral side and then give vague stories that do not show ownership or impact. Another common problem is jumping into code too fast without clarifying requirements or testing edge cases. Some candidates also freeze when challenged and get defensive instead of thinking out loud. For senior candidates, weak system design hurts a lot. At every level, poor communication, messy code, and not tying examples to Leadership Principles can drag down an otherwise decent interview.

AmazonSoftware Engineerinterview guideinterview preparationAmazon interview

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