Senior Frontend Developer / Tech Lead

Location: Estonia Job Overview React, Next.js, architecture and interactive graphics | 5 to 8 years This role owns technical direction for complex front-end features and supports the team through design decisions, reviews and mentoring. The successful candidate should combine strong React and Next.js engineering with architecture, performance and integration expertise. Must Have Skills • Advanced experience with React, Next.js, TypeScript and modern hooks-based component design. • Ability to design scalable front-end architecture with a single source of truth and clear boundaries between UI, business logic and data access. • Experience designing reusable component libraries and governing consistent component APIs. • Deep experience with Zustand, Redux Toolkit or an equivalent state-management approach, including efficient selector design. • Strong HTML, CSS and SCSS skills, including responsive design, accessibility and style isolation. • Experience implementing interfaces from detailed visual specifications and using design systems such as IBM Carbon or Material UI. • Strong REST API integration experience, including typed models, adapters, polling and defensive handling of missing or inconsistent data. • Experience defining or validating API contracts with backend teams and applying contract-testing principles. • Demonstrated performance expertise, including profiling, memoisation, code splitting, lazy loading and bundle analysis. • Awareness of frame rate, GPU utilisation and memory behaviour on graphics-heavy screens. • Hands-on experience with WebGL, three.js or React Three Fiber, including scene and camera control, pointer picking and animation timelines. • Experience managing events and interaction across layered UI and graphics surfaces. • Experience integrating map SDKs, handling coordinate systems, implementing provider fallbacks and managing API tokens safely. • Ability to build components that integrate into an existing host application through clean props and callbacks, isolated styles and no unintended global side effects. • Strong testing experience with Vitest or Jest and React Testing Library, supported by a practical test strategy. • Experience with strict TypeScript, error boundaries, cross-browser testing and browser DevTools. • Experience contributing to CI/CD pipelines, Git workflows and high-quality pull-request reviews. • Experience with Azure DevOps • Proven technical leadership through mentoring, task breakdown, estimation and technical documentation. • Understanding of front-end security fundamentals, including secure environment configuration, safe logging and responsible third-party dependency use. Good to Have Skills • Experience with advanced animation libraries such as GSAP or Framer Motion. • Experience with charting and data-visualisation libraries. • Experience with visual regression testing or end-to-end testing using Playwright • Experience with internationalisation and localisation at scale. • Familiarity with micro-frontends, monorepos or design-system governance. • Experience with production observability, release support and incident investigation. • Experience leading technical discovery or proof-of-concept work for complex interactions. Salary: $30 – $35 / hour