Senior Back-End Engineer

Workster is partnering with a fast-growing international technology company within the sports betting and iGaming industry to recruit a Senior Back-End Engineer for their team in Sofia, Bulgaria. This is an opportunity to work on high-performance, real-time sports betting products, building the systems and services that power complex betting operations. You will take ownership of backend development, architecture, integrations, and performance while working in an engineering environment where scalability, reliability, and speed are essential. Your Role Design, develop, and maintain high-performance backend services and applications Build scalable systems capable of handling high volumes of real-time transactions and data Develop and maintain APIs, microservices, and integrations with internal and third-party systems Contribute to the architecture and continuous evolution of the company’s sports betting platform Work with real-time sports data, betting feeds, pricing, and other platform integrations Design reliable solutions capable of supporting significant traffic during major sporting events Optimise backend services for performance, scalability, availability, and security Design and maintain database structures and data-processing solutions Write clean, maintainable, well-tested, and reusable code Troubleshoot complex production issues and implement long-term technical solutions Collaborate closely with Front-End, Product, QA, DevOps, and other engineering teams Participate in code reviews and contribute to engineering standards and best practices Mentor less experienced engineers and support knowledge sharing across the development team Contribute to technical planning, estimation, and architectural decision-making Your Qualifications 5+ years of professional back-end software development experience Strong experience with a modern server-side programming language and its ecosystem Solid experience designing and developing RESTful APIs and microservices Strong knowledge of relational and/or NoSQL databases such as PostgreSQL, MongoDB, Redis, or similar Experience developing high-traffic, high-availability, or real-time applications Good understanding of distributed systems, asynchronous processing, and event-driven architectures Experience with messaging technologies such as Kafka, RabbitMQ, or similar is an advantage Strong understanding of software architecture, design patterns, and clean coding principles Experience with Git, CI/CD pipelines, automated testing, and modern development workflows Familiarity with Docker, Kubernetes, AWS, or other cloud technologies is highly advantageous Good understanding of application security, monitoring, logging, and performance optimisation Strong 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,…