Senior Backend Developer — .NET / PostgreSQL (Healthcare SaaS)

LCK Services Ltd is seeking a Senior Backend Developer proficient in .NET and PostgreSQL for their Healthcare SaaS platform, CarePortal, based in Telangana, India. CarePortal serves UK care homes with billing, workforce management, and regulatory compliance features. Its billing engine operates at ledger-grade, featuring append-only financial records, precise calculations, and tamper-evident audit trails. You will function as the dedicated backend engineer, collaborating with the founder within an AI-augmented development workflow. The codebase emphasizes strong architectural governance, including documented invariants, architectural decision records, and a design-locked schema. Responsibilities encompass building and maintaining ASP.NET Core APIs using CQRS via MediatR over PostgreSQL with Entity Framework Core, implementing financial workflows such as invoicing, payment allocation, reconciliation, and funder ledgers, and authoring rigorous tests covering unit, integration (with Testcontainers and PostgreSQL), and behavior-driven development scenarios.