Senior ReactJS Engineer

Fliff unpacks sports gaming into social, free-to-play games for all types of sports fans. We've built a social sports gaming experience that allows users to compete for leaderboard positioning, to achieve badges and build their status within the game.
We are pioneering play-for-fun sports gaming, with our flagship social sportsbook experience that includes sweepstakes promotions and loyalty rewards. We provide sports fans with fun, engaging, and free-to-play alternatives to real money gaming.
Who We Are Looking ForIf you are passionate about building scalable and engaging web applications, we want you on our team! Fliff is seeking a talented Sr. ReactJS Engineer to join our growing Social Sportsbook team. You’ll be part of a cross-functional group responsible for the full software development life cycle, focusing on delivering top-tier web experiences for both mobile and desktop platforms. The Sportsbook Reliability is a dynamic team that brings together skilled engineers and product managers who collaborate closely to build, release, and support live apps that our users love.

This role requires full working-hour alignment with Central European Time (CET ±2 hours) to enable daily, real-time collaboration with our Sofia-based team. We are only considering candidates located within this time zone range. Applicants outside CET ±2 hours will not be considered. The Role:

• Develop and maintain responsive web applications using ReactJS, ensuring a seamless experience across devices.
• Collaborate with backend, DevOps, and designers to implement new features and optimize the live product.
• Support the live platform by identifying and resolving real-time performance issues.
• Design scalable solutions with attention to responsive UIs using pure CSS/SCSS without relying on external frameworks.
• Mentor junior engineers and provide code reviews to maintain high standards.
• Leverage Redux, React-Redux bindings, and middleware (Thunk/Saga) for state management.
• Implement RESTful APIs using axios and fetch, with optional GraphQL integration via Apollo client.

Experience Required:

• 5+ years of experience building modern web applications, with strong expertise in ReactJS and React Hooks (useState, useEffect, custom hooks).
• Advanced TypeScript skills, including utility types (Partial, Pick), generics, and infer keyword usage.
• Solid understanding of Redux mechanics, React-Redux bindings, and internal hooks.
• Strong CSS/SCSS knowledge, with the ability to build reusable, responsive UIs without external libraries (e.g., Material UI, Tailwind).
• Knowledge of WebSockets (native and socket.io) to handle real-time data.
• Experience with RESTful APIs, axios, and fetch, with optional GraphQL and Apollo Client experience.
• Familiarity with React Router for dynamic imports, lazy loading, and code splitting.
• Comfortable with UI tools like Figma, along with React DevTools, Chrome debugger, and testing tools such as Jest and Cypress.
• Adaptability and problem-solving skills to handle real-time challenges and evolving project requirements.
• Strong communication skills and a collaborative mindset to work effectively with cross-functional teams.

Benefits

• Competitive compensation package.
• Opportunity for professional development in a dynamic, fast-growing company.
• Supportive, collaborative, and knowledge-driven work environment.
• Engaging and challenging role with the freedom to innovate and build exciting solutions in the sports gaming industry.