Senior Frontend Developer (Warsaw)

Who we are:
Adaptiq is a technology hub specializing in building, scaling, and supporting R&D teams for high-end, fast-growing product companies in a wide range of industries.
 

About the Product:
The product is a fast-growing online entertainment platform focused on delivering browser-based games along with real-time interactive features. It serves an expanding audience and operates under conditions of high traffic, strict latency requirements, and secure micro-transaction processing within a social gaming environment.

The platform relies on a hybrid technology stack that combines a legacy codebase built with a widely used DOM-manipulation library and modern solutions based on React and Next.js. Current challenges include transforming legacy parts into a scalable, component-based architecture, implementing real-time interactions using WebSockets, maintaining consistency across mobile devices and browsers, and integrating payment and promotion management systems.

Strong engineering ownership is key to ensuring system stability, improving performance, and enabling fast, scalable feature delivery.

About the Role:
In this role, you will take ownership of frontend feature delivery from idea to production. You will work closely with frontend leadership, backend engineers, designers, QA, and DevOps to build and evolve a complex product.

A key part of your work will be driving the transition from a jQuery-based architecture to a modern React/Next.js setup. You will be expected to make architectural decisions, improve development workflows, and ensure high standards of performance, security, and code quality.

This position requires strong independence, solid technical judgment, and the ability to work in a fast-paced, evolving environment.
 

Key Responsibilities:

• Improve and maintain existing jQuery-based interfaces
• Build scalable and responsive UI using React and Next.js
• Refactor and structure CSS/SCSS for long-term maintainability
• Ensure cross-browser compatibility and strong mobile experience
• Implement and support real-time features using WebSockets
• Apply frontend security best practices
• Contribute to the design of a reusable component architecture
• Integrate APIs and collaborate closely with backend teams
• Set up and improve build tools and performance monitoring
• Implement and manage state using Redux, MobX, or similar
• Work with designers to deliver high-quality UI
• Develop key features such as payments, authentication, and promotions
   

Required Competence and Skills:

• 6+ years of experience in frontend development on production systems
• Strong experience working with legacy codebases (jQuery)
• Solid knowledge of React (Hooks, functional components)
• Hands-on experience with Next.js (SSR, SSG, API routes)
• Strong CSS/SCSS skills and responsive design expertise
• Proficiency in JavaScript (ES6+) and TypeScript
• Experience with WebSockets and async patterns
• Understanding of performance optimization and Core Web Vitals
• Familiarity with build tools like Webpack, Vite, or Gulp
• Experience integrating REST APIs
• Strong debugging and cross-browser troubleshooting skills
• Experience with state management libraries
• Git proficiency and experience working in teams
• Strong communication skills and ability to work independently
   

Nice to Have:

• Experience introducing TypeScript into existing projects
• Basic knowledge of PHP
• Experience with testing tools (Jest, RTL, Cypress)
• Experience with animation libraries like GSAP
• Familiarity with design tools (Figma, Zeplin, etc.)
• Understanding of CI/CD processes
• Knowledge of SEO and analytics
• Experience with hybrid mobile solutions (e.g., Cordova)
   

Why Us:

• We provide 20 days of vacation leave per calendar year (plus official national holidays of a country you are based in). 
• We provide full accounting and legal support in all countries we operate. 
• We offer a highly competitive package with yearly performance and compensation reviews.