Personalbüro U. Herrmann

Senior Full-Stack JavaScript Developer – Sports Betting

Sofia, Yugozapaden

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hirly's read of this role

Role family: Engineering
Seniority: Senior
Country: BG
Work mode: On-site / unstated
First seen by hirly: 8 Oct 2026

Derived automatically from the posting. Upload your resume above to see how the role scores against it.

the posting

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

### The Offer

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

Original posting on Personalbüro U. Herrmann's site ↗

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