Senior ReactJS Engineer - Fliff

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 For

If 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, la