Senior Front-end Developer (HTML/CSS)

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 front-end specialist with strong expertise in HTML and CSS, who understands browser internals, rendering pipelines, and modern performance metrics, and can consistently deliver low TTFB, excellent LCP, stable CLS, and fast overall load times.

• Build and maintain high-performance front-end architectures optimized for speed, scalability, and minimal resource usage.
• Apply deep knowledge of browser rendering, networking, caching, and critical-path optimization.
• Reduce Time to First Byte (TTFB), First Contentful Paint (FCP), Largest Contentful Paint (LCP), Time to Interactive (TTI), and First Input Delay (FID) across all products.
• Ensure Cumulative Layout Shift (CLS) remains near zero through careful layout design and render-stable UI patterns.
• Implement advanced optimization techniques such as code splitting, lazy loading, preloading, prefetching, HTTP/2 push alternatives, and asset prioritization.
• Minimize JavaScript execution cost and memory usage through efficient data structures, batching, and render minimization.
• Develop mobile-first features optimized for low-power devices and slow networks.
• Collaborate closely with back-end engineers to optimize API payloads, caching headers, compression, and server-side performance.
• Analyze performance using DevTools, Lighthouse, Core Web Vitals, WebPageTest, and RUM data.
• Maintain consistent UX, visual quality, and strong brand standards while improving performance.
• Stay up-to-date with emerging browser APIs, rendering techniques, and performance-centric best practices.

• 3+ years of front-end development experience.
• Expert knowledge of HTML5 and CSS3, including Flexbox, Grid, containment, and GPU layers.
• Deep understanding of JavaScript, V8 behaviour, async flows, and memory management.
• Experience with AJAX/Fetch, streaming APIs, and WebSocket communications.
• Solid background in cross-browser debugging, responsive/adaptive layouts, and accessibility.
• Experience improving and monitoring Core Web Vitals (LCP, CLS, FID, INP).
• Comfortable working on applications with heavy traffic and strict performance SLAs.
• Analytical mindset, strong problem-solving skills, and a collaborative work style.

• Experience with TypeScript.
• Strong ownership attitude and high attention to detail.
• Familiarity with bundle optimization (tree shaking, dead-code elimination, chunk analysis).
• Familiarity with image optimization (AVIF/WebP, adaptive loading, responsive images, lazy loading).
• Familiarity with resource hints (preload, preconnect, dns-prefetch).
• Familiarity with Service Workers, caching strategies, and background processing.
• Strong understanding of network optimization and CDN behaviour.

• Competitive 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.