Senior Full-Stack Engineer
Lead the development and architectural strategy for sophisticated, high-scale web platforms – modern frontends, robust backends, and agentic workflows.
About the role
We are a boutique, elite technology services firm seeking a world-class Senior Full-Stack Engineer. You will lead the development and architectural strategy for sophisticated, high-scale client platforms spanning SaaS, e-commerce, and internal tools.
This is a role for an engineer who thrives on solving deep technical complexity while delivering modern, performant frontend experiences and leveraging agentic development workflows. You aren't just closing tickets – you are architecting systems built to scale past a million users.
We expect an intuitive understanding of full-stack architecture: from database schema design and API contracts to SSR/ISR strategies, caching layers, and third-party integrations. As a member of our firm, you operate with high autonomy, often acting as the final technical authority on project-specific architectural decisions.
Core responsibilities
- Architectural leadership: Design and implement complex application architectures following industry best practices — modular, testable, and built for long-term maintainability.
- Agentic workflows: Implement and manage agentic development patterns, leveraging AI agents and LLMs to automate repetitive engineering tasks and enhance team productivity.
- Full-stack execution: Build robust backend logic in Node.js/NestJS or Laravel while crafting fluid, high-conversion frontends using React, Next.js, Vue, or Nuxt with TypeScript throughout.
- Performance optimization: Obsess over Core Web Vitals, server-side caching (Redis/CDN), and database query optimization to ensure sub-second load times under real traffic.
- Complex integrations: Lead integrations with payment gateways, CRMs, ERPs, and third-party APIs — ensuring data integrity, idempotency, and system resilience.
- Technical specifications: Author detailed technical specs for other engineers, ensuring a clear implementation path and reducing technical debt across engagements.
- Security & compliance: Maintain a proactive stance on platform security, authentication patterns, and compliance requirements for regulated industries.
What we're looking for
We are looking for an engineer who has shipped production systems at scale and can demonstrate high-level technical maturity.
Technical mastery
- →Demonstrated full-stack mastery: Expert-level proficiency in React or Vue with TypeScript, plus Node.js/NestJS or similar backend frameworks.
- →Agentic development: Proficiency with agentic development principles, including the integration of AI coding assistants and autonomous workflows into daily engineering.
- →Backend excellence: Advanced API design skills — REST, GraphQL, event-driven patterns, RBAC, and audit trails.
- →Database depth: Strong PostgreSQL or MySQL knowledge, including index optimization, migrations, and managing high-concurrency workloads.
- →Modern frontend fluency: Experience with SSR/ISR (Next.js, Nuxt), Tailwind CSS, and component-driven architecture.
- →Search & cache mastery: Hands-on experience with Redis, Elasticsearch, and CDN/edge caching strategies.
- →API proficiency: Deep experience with GraphQL and REST for headless or integrated environments.
Professional attributes
- →Strategic problem-solver: You don't just fix symptoms; you find root causes and design durable solutions.
- →Craftsmanship: Obsessive about writing clean, well-documented, and upgrade-proof code.
- →Elite communication: Fluent in English with the ability to explain complex technical trade-offs to clients and stakeholders.
- →Autonomous & predictable: You manage your own time effectively, meet deadlines consistently, and proactively alert the team if a timeline needs adjustment.
Why you'll love working with us
100% remote & flexible
Work where you want, when you want. We value results over desk time.
High-end projects
Work on complex, high-traffic builds for SaaS, e-commerce, and enterprise clients that require true engineering skill.
Competitive compensation
Top-of-market rates for top-tier expertise, with transparent review cycles.
Professional growth
Access to stipends for equipment, continued education, conferences, and wellness.
How to apply
To ensure we only consider the most serious and qualified candidates, please follow this application process carefully. Generic applications, or those without the requested video, will be archived.
- 1Email contact@geniusxlab.com with the subject line "Senior Full-Stack Engineer." In the first line of your message, please write: "I build systems that scale."
- 2Include a link to your GitHub, portfolio, or relevant case studies.
- 3Attach your résumé or CV in PDF format.
Video application (Loom, max 5 minutes)
- Question 1 — Architectural complexity
Describe the most difficult full-stack system you've ever built. What were the primary technical hurdles, and how did you architect the solution to be maintainable and upgrade-proof?
- Question 2 — Performance strategy
Walk us through your process for optimizing a slow web application. Where do you look first, what tools do you use, and how do you balance functionality vs. speed?
- Question 3 — Agentic workflows
How are you currently using AI agents or autonomous development patterns to improve your engineering output? Give a specific example.
We review every application within 5 business days and respond to qualified candidates with next steps.