Senior Fullstack Software Engineer

About Wakacje.plWe are an e-commerce platform and a network of travel agencies offering a wide range of travel products. Since 2015, we have been part of Wirtualna Polska Holding – Poland’s largest group of media and e-commerce companies. Together with Travelplanet.pl and the Invia brands across CEE, we are building a unified travel group driven by a shared #TravelMindset. In our daily work, we #Explore better ways to grow, #Engage through real ownership and teamwork, and #Enjoy building experiences that people genuinely look forward to.  Send us your CV and… see you at Wakacje.pl! ✈️  Key responsibilities: • Designing, implementing, and maintaining functionality of JavaScript/TypeScript-based applications used by internal and external clients. • Ensuring the codebase is clean, maintainable, scalable, and aligned with engineering best practices. • Monitoring application health using technical and business metrics (e.g., Grafana dashboards) and reacting to anomalies or incidents. • Optimizing existing solutions, improving performance, and ensuring reliability of critical system flows such as checkout and payments. • Collaborating closely with business stakeholders and product teams to translate requirements into technical solutions and continuously improve the product. • Working with databases to analyze data, debug issues, and ensure correct data flow between services. • Proposing and implementing new ideas, selecting appropriate technologies, and contributing to architectural decisions. • Creating and maintaining unit and integration tests to ensure stability and long-term maintainability of the system. Requirements: • Min. 5 years of experience with React.js and Next.js or Nest.js or Express.js​ • Strong experience with Node.js (production-grade APIs, async patterns, error handling, performance optimization) • Solid knowledge of JavaScript / TypeScript and modern backend architecture (REST, middleware, validation, auth) • Experience with API integrations (payments, CRM, external services) and handling edge cases • Practical experience with logging, monitoring, and debugging in production environments • Understanding of performance optimization and scalability in high-traffic transactional systems Nice to have: • Experience with Bun or alternative JS runtimes • Familiarity with Redis (caching, session handling, rate limiting) • Experience with Server-Sent Events (SSE) or real-time communication patterns • Knowledge of system observability tools (e.g., Grafana, ELK stack) • Experience in e-commerce / booking / checkout systems with conversion-focused optimization • SEO / Core Web Vitals / Google Analytics / Web Accessibility What do we offer: Workplace safety and comfort: • Employment based on an employment contract or B2B, • Full support during the onboarding period under the supervision of an engaging leader/buddy. Business agency and agility: • Real influence on business decisions, the ability to take initiatives and implement your ideas. Development within the organization: • Individual Development Plan, • Participation in training courses and conferences to enhance professional competencies. All-inclusive for Employees: • A benefits package that you can use according to your preferences – Lux Med medical care, Health and Life Insurance (PZU and Warta), Multisport card, shopping and lunch vouchers, and many other cafeteria offers available on the Worksmile platform, • Study Tour – trips abroad to explore our product offerings (destination tours and hotel audits), • A training and webinar package supporting professional and personal development, • Discounts on our products for employees and their families, • Work in the modern Alchemia office complex – Neon building, 100 meters from the Gdańsk Przymorze-Uniwersytet SKM station, • Teambuilding events for the start and end of the tourist season – check them out: Instagram, LinkedIn, Tiktok, Facebook, • Mini events, delicious coffee, and on Mondays, hot chocolate, • Casual dress code. Ready to join the team with a #travelmindset? We’re waiting for you!