Senior Full-Stack JavaScript Developer – Sports Betting, Remote

CloserHire is 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.

Language required: English

Responsibilities:

• 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

Requirements:

• 5 years of professional software development experience with strong expertise in JavaScript/TypeScript Strong experience with modern frontend frameworks such as React or similar
• Strong backend development experience with 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

Benefits:

• Senior-level position within a growing international sports betting technology company
• Opportunity to work on complex real-time and high-traffic products
• Modern technology stack and engineering-focused environment
• High level of ownership and influence over technical decisions
• Opportunity to contribute to architecture scalability and product development
• Collaborative international engineering team
• Professional development and career growth opportunities
• Exposure to the latest technologies within the sports betting and iGaming industry
• Modern working environment in Sofia Bulgaria Long-term opportunity within a fast-growing technology business