Senior Backend Developer (.NET)

A US tax software company is moving a critical legacy system to a modern .NET 8+ backend built on Clean Architecture, and needs a senior backend engineer to drive the API migration. The environment is high-availability, with complex business rules and strict security requirements.

What you'll do

• Translate complex legacy business logic into .NET 8+ Web APIs (Domain, Application, Infrastructure).
• Build secure APIs with strict authentication flows and compliance-driven session timeouts.
• Tune MySQL data access: Dapper for performance-critical paths, EF Core for the rest of the domain.
• Define API contracts with the Next.js frontend team and integrate payment providers (Braintree, Paymentech).

What we're looking for

• 5+ years of backend development with .NET / C# on enterprise services.
• Production experience with Clean Architecture and CQRS (MediatR or similar).
• Strong MySQL, with Dapper for complex queries and EF Core for domain work.
• Hands-on AWS: Fargate and RDS.
• Unit and integration testing as part of how you work.
• C1 English.
• Nice to have: payment gateways, regulated environments (SOC 2, PCI-DSS, GDPR), Redis, SQS or RabbitMQ.

Good to know

• Full-time, fully remote, contractor engagement, paid in USD (USD 2,500-3,000/month).
• Hiring through Niuro.
• Apply: https://app.niuro.io/source/dxEQSZTd?ref=ps_ibBPZs9Awr3aydkKBM-7GAPCrdIYQM7lfN8rogddxIo&utm_source=wellfound&utm_medium=job-board&utm_campaign=senior-backend-developer-net&utm_content=wellfound-20261026