Senior Full-Stack Developer

Bullfinch Recruitment

Lisbon, Portugal
Permanent
Remote
€33,000 - €50,000/year
Full-Stack JavaScript (React/Next.js & Node.js)System Design & ArchitectureDevOps & Observability

About the Role

We are looking for an experienced Senior Full-Stack Developer to join our high-performing engineering team based in Portugal. This role is ideal for someone who enjoys taking ownership of large technical challenges, designing scalable systems, and contributing to both architecture and execution. As a senior engineer, you’ll not only build robust features but also help guide technical direction, champion code quality, and contribute to a culture of performance, reliability, and continuous improvement.

Key Responsibilities

  • Lead the design, development, and optimization of scalable full-stack applications using Next.js, React.js, Node.js, and MySQL.
  • Drive architecture discussions and system design for new modules and features with an eye on scalability, modularity, and performance.
  • Own end-to-end implementation — from planning to deployment — ensuring best practices in coding, testing, CI/CD, and documentation.
  • Continuously improve client and server-side performance, including TTFB, LCP, code splitting, caching, DB tuning, and Lighthouse score optimizations.
  • Review code, provide architectural guidance, and advocate for engineering excellence within the team, leveraging AI developer tools to increase productivity.

Required Skills & Qualifications

  • 4–7 years of professional experience in full-stack web development, including recent experience in a senior or lead capacity.
  • Advanced proficiency in JavaScript (ES6+), React.js, Next.js (SSR, routing, data fetching), and Node.js.
  • Strong experience with relational databases, particularly MySQL, including schema design and performance tuning.
  • Proven ability to identify and debug performance bottlenecks across both frontend and backend.
  • Hands-on experience optimizing client-side performance using techniques like bundle splitting, lazy loading, and Lighthouse auditing.
  • Proficiency with Docker, CI/CD with Jenkins, and working knowledge of AWS services (EC2, S3, RDS).
  • Familiarity with modern AI-powered developer tools (e.g., GitHub Copilot, Cursor, Tabnine).

Preferred Qualifications

  • Experience handling multi-region websites, performance optimization and data privacy/security standards.
  • Experience with BigQuery GA4 exports—writing queries to analyze usage trends and performance issues.
  • Experience with DevOps, observability (New Relic, ELK), or system reliability practices.
  • Knowledge of CDNs (like Cloudflare) and internationalization/localization strategies for web apps.