Full Stack Software Developer

This role helps establish Built by Mainstreet:

Mainstreet is building an internal software development capability. This role is for a practical full stack developer who wants to build real applications, support them in production, and help shape how software gets built inside a Microsoft-based financial institution. Built by Mainstreet exists to solve internal business problems with software we can understand, improve, reuse, and support ourselves. We use modern tools, including AI-assisted development, to build software faster and more accurately.

This is the first dedicated software development hire in Built by Mainstreet, so the role also helps establish practical, repeatable development standards as the capability matures.

You will turn internal workflows into reliable software products:

As our Full Stack Software Developer you will build, deploy, and maintain internal software applications for Mainstreet Credit Union. You will work within a primarily Microsoft technology ecosystem. C#/.NET is our preferred application development stack, with Power Shell used extensively for scripting, automation, and environment administration. You will take applications from prototype through production for tools that support member origination, lending analysis, and staff operations.

You will work with business analysts, business users who create prototypes or workflow tools, Business Intelligence, and department leaders to turn real workflows into reliable, secure products that meet our data handling and access control expectations. You will work with the Technology Architect and Systems Administrator on platform patterns, security and integration approaches, Active Directory and Microsoft Entra n, and production environment configuration.

Success in your first year means you have taken ownership of at least one application end to end, including code, testing, deployment, documentation, monitoring, and support. You contribute to a working application pipeline and documented deployment process. You help mature practical standards for Git-based source control, code review, automated builds and tests, CI/CD, deployment, documentation, support, and general development practices. You respond to staff-reported issues with reliable triage and resolution cadence.

You leave the codebase and operating model clearer, safer, and easier to maintain.

You will work with support across business, data, infrastructure, and architecture:

You will not be expected to own every infrastructure, security, database, or business domain decision independently. You will work with the Technology Architect, Systems Administrator, Business Intelligence, business analysts, and business teams to make practical decisions and build reliable software within shared standards. The Technology Architect will set the overall architecture, platform patterns, engineering standards, security and integration approaches, and technical direction.

You will own implementation and day-to-day software engineering within those patterns, while contributing practical feedback as the standards evolve.

• Build web applications using C#, ASP.NET Core, and Blazor against a REST API backend.
• Implement data models, business logic, and API endpoints following clean architecture principles.
• Build and maintain application database schemas using Entity Framework Core migrations against SQL Server, with Azure SQL or other approved data platforms used where appropriate.
• Integrate applications with internal APIs, vendor APIs, CGI RFS 360, credit bureau services, e-signature platforms, Microsoft 365 and Teams, existing SQL data sources, legacy applications, identity services, and AI-assisted development or large language model APIs where they support practical application delivery.
• Work collaboratively with Business Intelligence and the Technology Architect/SQL Administrator when designing application databases, integrating with existing data sources, and developing or optimizing production SQL queries.
• Write unit and integration tests and maintain test coverage across Core, Infrastructure, and API layers.

• Contribute to the development and improvement of Git-based source control, code review, automated build, testing, and CI/CD practices for internal application projects.
• Deploy and support applications primarily within Mainstreet’s Windows Server/IIS environment, with the ability to support cloud-hosted platforms such as…