Senior JavaScript Front-End Developer

We are a Bulgarian technology company with over 25 years of experience, behind numerous pioneering digital products, including Bulgaria’s first internet cards and the country’s first interactive television game. Today, the company continues to develop innovative software solutions, online platforms and original digital products, combining technological expertise, creativity and out-of-the-box thinking.

We are looking for a senior JavaScript developer who is passionate about front-end development and capable of creating efficient, scalable, and visually consistent interfaces that work smoothly under heavy load with minimal resource consumption.

• Collaborate daily with product owners, back-end developers, designers, and project managers.
• Write clean, reusable, and maintainable JavaScript code for platform features and UI components.
• Ensure stable and efficient execution of client-side logic for high-traffic environments.
• Optimize rendering, API interactions, and resource usage for minimal CPU, memory, and bandwidth consumption.
• Implement efficient data flows, asynchronous operations, and event-driven UI behaviour.
• Analyze, profile, and improve front-end performance across multiple devices and browsers.
• Assess the feasibility of new features and propose technical improvements.
• Stay up-to-date with modern front-end technologies and performance-oriented development practices.

• 3+ years of relevant professional experience.
• Strong understanding of JavaScript, its quirks, and best practices.
• Solid understanding of asynchronous request handling, partial page updates, and AJAX/Fetch.
• Proficiency in cross-browser compatibility techniques.
• Good understanding of browser rendering behaviour, layout flow, and performance optimization.
• Experience with version control systems (SVN or similar).
• Basic understanding of HTML5/CSS3.
• Experience with browser debugging tools and performance profiling.
• Experience building responsive or adaptive layouts.

• Bachelor’s degree in Computer Science or a related field.
• Experience with Canvas rendering libraries (e.g., PixiJS).
• Experience building high-performance interfaces for large user bases.
• Ability to thrive in a fast-paced environment.
• Excellent attention to detail and strong organizational skills.

• Creating lightweight modular UI components designed for tens of thousands of parallel daily users.
• Optimizing client-side logic to maintain smooth performance on low-end devices.
• Reducing memory usage through efficient state handling and minimal DOM overhead.
• Designing update mechanisms that avoid unnecessary re-renders (diffing, batching, throttling, debouncing).
• Implementing efficient API call strategies to reduce server load and network usage.
• Creating scalable logic for real-time or near-real-time data updates.
• Ensuring minimal CPU, GPU, and RAM footprint across supported browsers.
• Improving platform responsiveness with optimized event loops, timers, and rendering strategies.
• Maintaining deterministic performance under heavy concurrency.
• Profiling, analyzing, and eliminating bottlenecks affecting client or server resources.

• Comptitive remuneration that reflects your experience and expertise.
• Private health insurance (including dental).
• Multisport card.
• Food vouchers.
• Convenient office location.
• A collaborative team culture that values technical expertise and knowledge-sharing.
• Opportunities for continuous learning and professional development.e