{"id":3821371,"url":"https://alion.io/job/e-card-ltd-senior-javascript-front-end-developer","title":"Senior JavaScript Front-End Developer","company":{"id":292889,"name":"E-card Ltd.","domain":"e-card.bg","url":"https://alion.io/company/e-card","size_band":null,"is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":null,"truth_index":null},"role":"Frontend","role_family":"Frontend","seniority":"senior","employment_type":null,"work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Sofia, Bulgaria"],"countries":["BG"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":null,"experience_years_min":3,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"JavaScript","optional":false},{"name":"PixiJS","optional":false}],"status":"live","first_seen_at":"2026-11-05T17:21:16Z","employer_posted_date":null,"last_verified_at":"2026-11-05T17:21:16Z","board_verified":false,"closed_at":null,"days_open":1,"trust":{"level":"not_scored","repost_count":null,"flags":[],"days_open":1},"description":"About Us\n\nWe 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.\n\nWe 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.\n\nResponsibilities\n\nCollaborate daily with product owners, back-end developers, designers, and project managers.\n\nWrite clean, reusable, and maintainable JavaScript code for platform features and UI components.\n\nEnsure stable and efficient execution of client-side logic for high-traffic environments.\n\nOptimize rendering, API interactions, and resource usage for minimal CPU, memory, and bandwidth consumption.\n\nImplement efficient data flows, asynchronous operations, and event-driven UI behaviour.\n\nAnalyze, profile, and improve front-end performance across multiple devices and browsers.\n\nAssess the feasibility of new features and propose technical improvements.\n\nStay up-to-date with modern front-end technologies and performance-oriented development practices.\n\nQualifications\n\n3+ years of relevant professional experience.\n\nStrong understanding of JavaScript, its quirks, and best practices.\n\nSolid understanding of asynchronous request handling, partial page updates, and AJAX/Fetch.\n\nProficiency in cross-browser compatibility techniques.\n\nGood understanding of browser rendering behaviour, layout flow, and performance optimization.\n\nExperience with version control systems (SVN or similar).\n\nBasic understanding of HTML5/CSS3.\n\nExperience with browser debugging tools and performance profiling.\n\nExperience building responsive or adaptive layouts.\n\nAdvantages\n\nBachelor’s degree in Computer Science or a related field.\n\nExperience with Canvas rendering libraries (e.g., PixiJS).\n\nExperience building high-performance interfaces for large user bases.\n\nAbility to thrive in a fast-paced environment.\n\nExcellent attention to detail and strong organizational skills.\n\nEfficiency-focused tasks you will work on\n\nCreating lightweight modular UI components designed for tens of thousands of parallel daily users.\n\nOptimizing client-side logic to maintain smooth performance on low-end devices.\n\nReducing memory usage through efficient state handling and minimal DOM overhead.\n\nDesigning update mechanisms that avoid unnecessary re-renders (diffing, batching, throttling, debouncing).\n\nImplementing efficient API call strategies to reduce server load and network usage.\n\nCreating scalable logic for real-time or near-real-time data updates.\n\nEnsuring minimal CPU, GPU, and RAM footprint across supported browsers.\n\nImproving platform responsiveness with optimized event loops, timers, and rendering strategies.\n\nMaintaining deterministic performance under heavy concurrency.\n\nProfiling, analyzing, and eliminating bottlenecks affecting client or server resources.\n\nWhat We Offer\n\nComptitive remuneration that reflects your experience and expertise.\n\nPrivate health insurance (including dental).\n\nMultisport card.\n\nFood vouchers.\n\nConvenient office location.\n\nA collaborative team culture that values technical expertise and knowledge-sharing.\n\nOpportunities for continuous learning and professional development.e\n\nInterested? 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