Senior Full-Stack JavaScript Developer – Sports Betting

We are partnering with a fast-growing international technology company within the sports betting and iGaming industry to recruit a Senior Full-Stack JavaScript Developer for their team in Sofia, Bulgaria.

This is an opportunity to work on high-performance, real-time betting products used in a fast-paced environment where scalability, reliability, and user experience are critical. You will take ownership across the full development lifecycle, working with modern JavaScript technologies to build and continuously improve complex sports betting platforms.

Your Role:

• Design, develop, and maintain scalable full-stack JavaScript applications
• Build responsive and high-performance user interfaces using modern frontend technologies
• Develop robust backend services, APIs, and integrations supporting real-time sports betting products
• Work with high-volume, real-time data and ensure applications remain reliable during peak sporting events
• Design and integrate RESTful APIs, WebSockets, and third-party services
• Contribute to architectural decisions and help define technical standards and best practices
• Write clean, maintainable, well-tested, and reusable code
• Identify performance bottlenecks and optimise applications for speed, scalability, and reliability
• Collaborate closely with Product, UX/UI, QA, DevOps, and other engineering teams
• Participate in code reviews and support the continuous improvement of development processes
• Mentor less experienced developers and share technical knowledge across the engineering team
• Troubleshoot complex production issues and contribute to long-term technical solutions
• Stay up to date with emerging technologies and evaluate their potential application within the product

Your Qualifications:

• 5+ years of professional software development experience, with strong expertise in JavaScript/TypeScript
• Strong experience with modern frontend frameworks such as React, Next.js, or similar
• Strong backend development experience with Node.js
• Solid understanding of TypeScript, HTML5, CSS3, and modern JavaScript
• Experience designing and consuming REST APIs and working with real-time technologies such as WebSockets
• Experience with relational and/or NoSQL databases such as PostgreSQL, MongoDB, or Redis
• Good understanding of software architecture, design patterns, and scalable application development
• Experience with Git, CI/CD pipelines, automated testing, and modern development workflows
• Familiarity with cloud environments and containerisation technologies such as AWS, Docker, and Kubernetes is an advantage
• Strong understanding of application performance, security, and reliability
• Excellent analytical and problem-solving skills
• Ability to take ownership of complex technical challenges and work independently
• Strong English communication skills
• Previous experience within sports betting, iGaming, fintech, or another high-transaction digital environment is highly advantageous