Full-Stack Questions

A blog series

Full-Stack Interview Questions for 4+ Years

Real questions for a full-stack engineer with four or more years of experience: HTML and CSS, Tailwind, TypeScript, React, Next.js, Node.js, Express, MongoDB, Prisma, Hasura, LLMs, agents, RAG, the AI SDK, Meilisearch, Mixpanel and the libraries teams use every day. Every answer is written in plain English.

Started 
2026
Lessons 
39
Reading 
~22 h

Contents

Every lesson has the same steps: what it is, how it works, a real example, common mistakes, then interview questions with answers you can say out loud.

  1. Lesson 00How to Use This Question BankWhat interviewers expect at 4+ years, how the questions are grouped, and a one-page map of every topic.8 min
  2. Lesson 01HTML & CSS Interview QuestionsSemantic HTML, the cascade, layout with flexbox and grid, container queries, stacking contexts, and common CSS traps.32 min
  3. Lesson 02Tailwind CSS Interview QuestionsTailwind v4, how utilities are generated, dynamic class names, class merging, design tokens and keeping Tailwind code tidy.27 min
  4. Lesson 03TypeScript Interview QuestionsGenerics, narrowing, utility types, tsconfig flags, typing React and APIs, and the errors that confuse people.31 min
  5. Lesson 04React Interview QuestionsComponent design, hooks, rendering cost, forms, data fetching, React 19, and code-review style questions.36 min
  6. Lesson 05Next.js Interview QuestionsApp Router, Server and Client Components, caching, Server Actions, proxy, rendering modes and deployment.34 min
  7. Lesson 06Node.js & Express Interview QuestionsEvent loop, streams, workers, Express 5, security, graceful shutdown and performance.29 min
  8. Lesson 07MongoDB Interview QuestionsSchema design, indexes, aggregation, transactions, replica sets, sharding and common anti-patterns.31 min
  9. Lesson 08Prisma & SQL Interview QuestionsPrisma 7, migrations, relations, transactions, N+1, raw queries, and the SQL behind it.30 min
  10. Lesson 09Hasura & GraphQL Interview QuestionsHow Hasura works, permissions, remote schemas, actions, events, subscriptions and GraphQL core ideas.29 min
  11. Lesson 10LLMs, Agentic AI, RAG and HarnessesAgent vs agentic AI, workflows vs agents, the harness, MCP, RAG end to end, evaluation and safety.45 min
  12. Lesson 11Vercel AI SDK Interview QuestionsstreamText, tools, structured output, multi-step loops, useChat, testing and security.40 min
  13. Lesson 12Meilisearch & Mixpanel Interview QuestionsSearch relevance, indexing and security with Meilisearch; events, identity and funnels with Mixpanel.39 min
  14. Lesson 13Popular Libraries Interviewers Ask AboutTanStack Query, Zustand, Zod, React Hook Form, auth libraries, Redis, BullMQ, Stripe, testing tools and more.39 min
  15. Lesson 14The Experience-Level RoundOwnership, trade-offs, debugging stories, code review and system-design-lite questions with model answers.32 min
  16. Lesson 15JavaScript Core Interview QuestionsTypes and coercion, prototypes, classes, this, copying, Map and Set, iterators, modules, newer array methods and “what does this print” puzzles.39 min
  17. Lesson 16Async JavaScript, Promises and the Event LoopOrder puzzles in the browser and Node, promise rules, combinators, concurrency limits, cancellation, race conditions and async memory leaks.36 min
  18. Lesson 17JavaScript Coding Round: Polyfills and UtilitiesTested solutions for debounce, throttle, curry, memoize, deep clone, promise polyfills, a pool, an event emitter, an LRU cache and live-coding tips.35 min
  19. Lesson 18Redis and Caching Interview QuestionsCache-aside and the other patterns, TTL and invalidation, stampedes, data types, persistence, eviction, rate limiting, locks and client settings that matter.40 min
  20. Lesson 19Queues, Background Jobs and WebhooksWhy queues, BullMQ, retries and backoff, dead letters, idempotency, the outbox pattern, receiving and sending webhooks, RabbitMQ vs Kafka vs SQS.30 min
  21. Lesson 20Realtime: WebSockets, SSE and Socket.IOPolling vs SSE vs WebSocket, handshake and heartbeats, Socket.IO rooms and acks, scaling with Redis, auth, backpressure and proxy timeouts.38 min
  22. Lesson 21Testing Tools: Jest, Vitest, Testing Library, PlaywrightMocks and fake timers, MSW, user-event, testing hooks and Server Components, Playwright locators and flaky tests, database tests with Prisma.28 min
  23. Lesson 22Auth Libraries, OAuth and OIDCOAuth vs OpenID Connect, code flow with PKCE, tokens and rotation, Auth.js and Better Auth, protecting Next.js 16, RBAC, passkeys and MFA.42 min
  24. Lesson 23Payments and Third-Party IntegrationsStripe Checkout and Payment Intents, webhooks, idempotency keys, S3 uploads, email deliverability, timeouts, retries and circuit breakers.44 min
  25. Lesson 24Git, Team Workflow and MonoreposMerge vs rebase, undoing mistakes, reflog, bisect, branching models, code review, pnpm workspaces, Turborepo, changesets and versioning.30 min
  26. Lesson 25State and Data Libraries in DepthRedux Toolkit, TanStack Query v5, Zustand and Jotai, server state vs client state, optimistic updates, hydration with the App Router, forms with Zod.36 min
  27. Lesson 26Deployment, CI/CD and MonitoringVercel deploys, Docker for Node, GitHub Actions, feature flags, safe rollouts and migrations, Sentry, OpenTelemetry and SLOs.43 min
  28. Lesson 27SEO, i18n, PWA and PostgreSQL DeeperNext.js metadata and sitemaps, locale routing and plurals, service workers, window functions, JSONB, EXPLAIN, locks, vacuum and PgBouncer.41 min
  29. Lesson 28Accessibility Beyond the BasicsWCAG 2.2 criteria in plain words, forms, focus and dialogs, live regions, ARIA, contrast numbers and testing, one level past Frontend Depth Lesson 6.20 min
  30. Lesson 29GraphQL Beyond HasuraSchema design, nullability, DataLoader, cursor pagination, errors, mutations, limits, subscriptions, federation, and when not to use GraphQL.22 min
  31. Lesson 30tRPC, REST and OpenAPItRPC for your own TypeScript app, REST plus OpenAPI for outside callers: generated clients, contract tests, breaking changes, problem-details errors and idempotency keys.24 min
  32. Lesson 31Security in Depth for Full-Stack DevelopersSSRF, path traversal, prototype pollution, ReDoS, unsafe deserialization, injection, password hashing, headers, rate limits, secrets, supply chain, uploads and a threat-model routine.32 min
  33. Lesson 32Full-Stack Performance: From Database to BrowserFind the bottleneck first, then fix the database, caching, compression, streaming and bundle size, and measure each change with p50, p95 and p99.42 min
  34. Lesson 33Node.js Internals Interviewers Ask AboutEvent loop phases, microtask and nextTick order, the threadpool, backpressure, workers, memory, and the Node 22 tools with stable or experimental labels.43 min
  35. Lesson 34Containers, Kubernetes, Terraform and AWS for Full-Stack InterviewsContainers versus VMs, Kubernetes objects, probes, rollouts, Helm, platform choice, IAM, Terraform state, secrets and cost.38 min
  36. Lesson 35Vector Databases, pgvector, Retrieval Evals and LLM CostDistance measures, HNSW and IVFFlat, the filter trap, hybrid search, golden sets, judges, prompt caching and tracing.40 min
  37. Lesson 36System Design Mock Interview: How to Talk Through ItSay a system design answer out loud: the 45-minute clock, the first five minutes, drawing boxes, one-sentence trade-offs, failure questions, numbers and a full walkthrough with timings.30 min
  38. Lesson 37Live Coding and Take-Home RoundsA 45-minute routine, a take-home checklist and six full-stack tasks with tested code.42 min
  39. Lesson 38Behavioural Questions, Salary and OffersBehavioural answers, conflict stories, salary talks, offers and the first 90 days.28 min

Glossary

62 terms used in this series. Inside any lesson, hover or tap a dotted term to see its meaning without leaving the page. Browse all terms →