Senior .NET Developer / Tech Lead

Location: Tallinn, Estonia; Vilnius, Lithuania; Rīga, Latvia Workplace: fully Project/Client: Fintech Location: Lithuania Start Date: ASAP Duration: 12 months Language: English Role Overview: We’re looking for a Senior .NET Developer / Tech Lead to join our engineering team and build payment-focused backend solutions in a regulated fintech environment. This is a hands-on role combining software development with technical leadership. You’ll design and develop backend services, contribute to technical and architectural decisions, and help the team maintain high engineering standards. Key Responsibilities: Design and develop backend services using C# / modern .NET Contribute to technical design and architectural decisions Build integrations with REST APIs , third-party platforms, messaging, and file-based interfaces Ensure code quality through code reviews and engineering best practices Mentor developers and lead technical discussions Work with SQL , relational databases, CI/CD , and Docker Build secure, reliable, and scalable software solutions Collaborate with product, compliance, QA, and other engineering teams Must-Have Requirements: 7+ years of hands-on C# / .NET experience Strong backend development experience Experience with REST APIs , integrations, and distributed systems Strong SQL and relational database experience Experience with Docker and CI/CD Understanding of secure and reliable software development Experience as a Senior Engineer , Tech Lead , or similar Ability to take technical ownership and guide other developers Nice to Have: Experience in payments , banking , fintech , or financial services Experience in a regulated / compliance-driven environment Knowledge of ISO 20022 / SEPA Understanding of clearing , settlement , or payment processing Experience with Azure or AWS What we offer Model: B2B contract with Bonapolia - one contract, one monthly invoice Rate: negotiated per candidate seniority and client budget Payment: monthly invoice, paid on the same schedule the client pays us (usually 30 days) Contract written under your country's law We handle the client-side paperwork: MSA, NDA, invoicing 🏢 About Bonapolia Bonapolia is a family-owned IT staff augmentation team based in Lisbon. We build engineering teams for product companies and IT consultancies across Europe and the US. More at bonapolia.com 📩 Ready to Join? We look forward to receiving your application and welcoming you to our team!