Senior Back End Developer (C#)

Access Softek has been building software for the financial industry for over 30 years. Headquartered in Berkeley, California, we work with hundreds of banks and credit unions across the U.S., helping them deliver modern digital banking experiences to millions of users.

We are looking for a Senior Back End Developer (C#) to join our Banking Platform Team.

This team builds and maintains the core services behind our award-winning online banking platform, used by 400+ Financial Institution clients. Their work includes leading complex feature delivery and driving our monolith-to-microservices migration — the kind of work that combines deep backend engineering with real-world FinTech and cloud architecture challenges. The team is a strong fit for an engineer who enjoys solving complex, high-scale backend problems and wants to gain deep exposure to cloud architecture in a mission-critical domain.

You will work with C# .NET Core, .NET Framework 4.8, MS SQL Server, RabbitMQ, and REST, partnering closely with product managers, QA engineers, and front-end developers in a distributed team. AI-assisted development tools (GitHub Copilot, Cursor, Claude Code, ChatGPT) are also part of the team's everyday workflow, helping developers move faster with coding, debugging, refactoring, testing, and documentation.

Important: this role requires overlap with 2 AM–10 AM PST/PDT — some flexibility is possible in both directions.

• Lead design and delivery of complex features, from ideation to production.
• Proactively identify problems and drive technical decisions with minimal oversight.
• Use AI-assisted tools to accelerate delivery, critically validating output for correctness and security.
• Produce clear documentation for API consumers.
• Drive automated test coverage for your components.
• Own and evolve code within your product area, including microservices architecture.
• Modernize legacy functionality and improve the maintainability of existing solutions.
• Follow engineering best practices around code review, version control, CI/CD, and secure development.
• Investigate issues, analyze logs and telemetry, and deliver safe, reliable fixes.
• Share knowledge and help improve team development practices.

• 5+ years building web apps/backend APIs in C#.
• Proven experience making architectural decisions and owning technical trade-offs.
• Strong OOD principles, classic design patterns (GoF).
• Experience with microservices architecture, as well as working with and modernizing legacy systems.
• Strong data modeling / MS SQL / data access optimization.
• Experience with API design, implementation, and troubleshooting.
• Unit & integration testing (NUnit/xUnit, FluentAssertions, Moq).
• Comfortable owning code from commit to production, with strong CI/CD and Git-based workflow experience.
• Understanding of web security fundamentals and secure coding practices.
• Comfortable using AI tools as a core part of daily engineering work — applied to production-quality code, not just casual experimentation.
• Experience integrating LLM/AI features into products (agents, RAG, MCP-based tooling), building internal AI-driven developer-productivity tooling would be a plus. 
• Good communication skills and Intermediate+ English.