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Senior Frontend Developer

Zexter


Job Location:

Madrid - Spain

Monthly Salary: Not provided by the employer
Posted: 18 September 2026 (Yesterday)
Application Deadline: 16 December 2026
Vacancies: 1 Vacancy

Job Summary

ZEXTER is a technology company developing its own full-stack platform for the digital entertainment and iGaming ecosystem. We build scalable technology solutions for operators creators and digital businesses helping them launch manage scale and monetize their products more efficiently.

We are now looking for a Senior Frontend Developer to help us build and scale our in-house platform. This is a hands-on product-focused role for someone with strong React and TypeScript expertise solid experience building production-grade applications and the ability to take ownership of frontend development in a growing product.

Responsibilities:
  • Develop and maintain scalable high-performance frontend applications using React and TypeScript.

  • Design and implement robust frontend solutions contributing to architecture decisions and improving existing systems.

  • Build and deliver end-to-end product features collaborating closely with backend developers QA design and product.

  • Ensure code quality performance and reliability through testing code reviews monitoring and continuous optimization.

  • Contribute to development processes and frontend best practices improving tooling CI/CD observability and overall engineering quality.

Requirements:
  • 5 years of commercial frontend development including 3 years with React with experience owning and supporting production applications under real user load.

  • Strong TypeScript skills: strict mode generics utility types discriminated unions and fully typed API contracts without any.

  • Advanced React 18/19 & knowledge: hooks render cycle Suspense Server/Client Components App Router SSR/SSG/ISR middleware caching and routing.

  • Experience with TanStack Query including query management invalidation SSR prefetching/hydration persistent cache and optimistic updates.

  • Ability to design and evolve large-scale frontend architecture: clear module boundaries layered structure public APIs and gradual legacy migration without blocking feature development.

  • Strong focus on code quality and testing: Vitest/Jest React Testing Library Playwright/Cypress ESLint/Prettier code reviews and Core Web Vitals optimization.

  • Experience with modern frontend infrastructure and operations: Git CI/CD (GitHub Actions/GitLab CI) Sentry Docker and deployments.

  • Solid understanding of API communication and web security: REST WebSocket authentication/refresh flows CORS CSP XSS SSRF and secure BFF patterns.

  • Experience working in a cross-functional product team with backend design and QA plus hands-on knowledge of Tailwind CSS Zod and internationalization (next-intl or equivalent).

  • English Russian - B2 mandatory!

Nice to have:
  • Experience in iGaming betting fintech or other high-load domains with real-time data.

  • Experience with admin panels and role-based access control.

  • at the level of writing a BFF layer proxies and small services.

  • Monorepo experience: pnpm workspaces Turborepo Nx.

  • Experience supporting legacy browsers and polyfills on a modern stack.

  • Experience setting up observability: logging tracing dashboards.

What we offer:
  • Fully remote work.

  • Competitive salary.

  • Opportunity to work in a fast-growing international iGaming company.

  • Strong Development and Product teams.

  • Minimal bureaucracy and the opportunity to directly influence product quality.

  • Clear career path with the opportunity to grow.

  • Interesting challenges and modern tools.