Backend Software Engineer (.NET / C# / APIs / Cloud)

Job Title: Backend Software Engineer (.NET / C# / APIs) Location: Sofia, Bulgaria Industry: Technology / E-commerce / Marketplace Function: Software Engineering / Backend Development Employment Type: Full-time Work Model: Hybrid (3 days onsite, 2 remote) About the Role We’re looking for a Backend Software Engineer to build and scale systems that power partner support experiences. This role focuses on developing API-driven platforms and integrations, including cutting-edge AI-powered solutions such as real-time voice support systems. You’ll work across distributed architectures, integrating telephony, AI agents, and internal platforms to deliver seamless, high-performance solutions. What You’ll Do Design, build, and maintain backend services using C# and .NETDevelop and manage APIs and system integrations across platformsBuild integrations between telephony systems, AI solutions, and internal toolsOwn features end-to-end, from design through to production supportContribute to system architecture, scalability, and technical strategyMaintain and evolve internal platforms and servicesWrite clean, testable, and well-documented codeImplement best practices across performance, reliability, and maintainabilityCollaborate in an agile, cross-functional engineering teamWhat We’re Looking For Strong experience in backend development using C# and .NETExperience building APIs (REST, MVC architecture)Solid understanding of software engineering fundamentals (data structures, design patterns)Experience with distributed systems and event-driven architectureKnowledge of cloud platforms (AWS, GCP, or Azure)Experience with CI/CD pipelines and modern development practicesStrong testing mindset (unit testing, code quality)Understanding of observability and system performance metricsStrong communication and teamwork skillsNice to Have Experience working with AI integrations or voice/telephony systemsExposure to domain-driven design (DDD)Experience in high-scale or customer-facing platformsWhat’s on Offer Hybrid working model (Sofia-based)Flexible and collaborative team cultureOpportunity to work on AI-driven, high-impact productsCareer growth and development opportunitiesAccess to modern technologies and scalable systemsWhy Apply This is an opportunity to work on innovative backend systems at the intersection of AI, real-time communication, and scalable platforms. You’ll have ownership, technical influence, and the chance to build solutions that directly impact user and partner experience at scale.