Senior Full-Stack Engineer (Next.js, TypeScript & Cloud)

This role is suitable for a Senior Full-Stack Engineer with 5+ years of production experience building web applications with TypeScript, React, Next.js, Node.js, REST, GraphQL, serverless functions, and relational or NoSQL databases. The candidate should also be skilled in performance optimization, secure development, test automation, AI/LLM API integration, responsive UI, and achieving strong Lighthouse scores. They should be familiar with leading features from technical design through deployment, reviewing code, mentoring engineers, and collaborating asynchronously with distributed product, design, and research teams.

1. How would you structure a large Next.js application using the App Router?

I would organize the application around route segments, colocated components, and clear server/client boundaries. Server Components would handle data fetching where possible, while Client Components would be limited to interactive functionality to improve performance and reduce bundle size.

2. How do you decide between Server Components, Client Components, and server actions in Next.js?

I use Server Components for static rendering, secure data access, and server-side fetching, and Client Components only when browser APIs, state, or event handlers are required. Server actions are useful for type-safe mutations that can run on the server without exposing sensitive implementation details to the client.

3. How would you improve Core Web Vitals and achieve a Lighthouse score above 90?

I would optimize image formats and sizing, minimize JavaScript, use streaming and caching, reduce render-blocking resources, and analyze bundle composition. I would monitor LCP, INP, and CLS with Lighthouse and real-user metrics, then verify improvements across representative devices and network conditions.

4. How would you design a REST and GraphQL integration in a TypeScript application?

I would define strongly typed contracts, centralize request handling, validate responses at runtime, and implement consistent error and authentication behavior. GraphQL is useful for flexible, client-specific data requirements, while REST may be preferable for simpler resources, caching, or external integrations.

5. How would you build a secure serverless API endpoint for an AI-powered feature?

I would authenticate and authorize the request, validate and limit user input, keep provider credentials server-side, and apply rate limiting and usage controls. I would also define timeouts, handle provider failures safely, log non-sensitive metadata, and avoid exposing confidential prompts or customer data.

6. How would you integrate an OpenAI, Claude, or Gemini API into a responsive web application?

I would call the model through a server-side service, stream responses when appropriate, and provide clear loading, cancellation, retry, and error states in the frontend. The integration should include structured outputs, token and cost limits, prompt versioning, and safeguards against prompt injection and sensitive-data leakage.

7. How do you choose between relational and NoSQL databases for a new feature?

I choose a relational database when transactions, relationships, constraints, and complex querying are central to the domain. NoSQL can be a better fit for high-volume access patterns, flexible schemas, or horizontally scalable document and key-value workloads, provided the data-access patterns are well understood.

8. What testing strategy would you apply to a full-stack Next.js application?

I would combine unit tests for business logic, component tests for UI behavior, integration tests for APIs and database access, and end-to-end tests for critical user journeys. Tests should run in CI with type checking, linting, coverage monitoring, and isolated test data to prevent unreliable results.

9. What security practices are important when building a global customer portal?

Important controls include secure authentication, least-privilege authorization, input validation, protection against XSS, CSRF, injection, and broken access control, as well as encrypted transport and secrets management. I would also minimize stored personal data, define retention policies, audit sensitive actions, and support applicable data-protection requirements.

10. How would you approach leading a feature from technical RFC through production rollout?

I would document the problem, requirements, architecture, trade-offs, risks, rollout plan, and observability strategy in the RFC. After implementation and review, I would use automated tests, staged deployment or feature flags, monitoring, and post-release validation before fully enabling the feature.

SIFTP Technologies is hiring a Senior Full-Stack Engineer to build high-performance web applications, AI-integrated customer portals, and digital platforms for a distributed global team. You’ll lead features from architecture through production, optimize performance, collaborate across time zones, review code, mentor engineers, and uphold security and testing standards. The stack includes TypeScript, React, Next.js, Node.js, REST, GraphQL, serverless functions, databases, and AI/LLM APIs. This is a full-time, 100% remote contractor role open worldwide, offering $70,000–$110,000 annually paid in local currency, plus generous PTO, learning support, and home-office benefits—an excellent opportunity to lead innovative AI-focused products.