Senior .NET Developer – Financial Systems & Integrations

ASSYST is seeking a highly skilled and self-driven Senior Software Developer to support and enhance complex, enterprise-scale financial applications. This role involves working on custom-built systems handling high-volume transactions, including payments, reconciliation, reporting, and multi-system integrations.

The ideal candidate is detail-oriented, capable of working independently, and experienced in solving complex financial and technical challenges.

Key Responsibilities

• Maintain and enhance legacy and custom financial applications
• Analyze and modify application logic with minimal documentation
• Design and develop scalable software solutions and integrations
• Implement API, database, and file-based system integrations
• Improve UI/UX with modern, responsive design practices
• Troubleshoot and resolve complex financial system issues
• Collaborate with technical teams and document solutions

Technical Skills

• HTML, CSS, JavaScript (Bootstrap or Tailwind)
• Responsive and mobile-first UI/UX design
• C#, ASP.NET (WebForms, MVC, .NET Core)
• Azure Entra ID / Azure AD B2C
• Microsoft SQL Server
• System integration (API, DB, file-based)
• Microsoft DevOps & system administration (IIS, networking)
• Familiarity with AI-assisted development

Required Experience

• 7+ years maintaining legacy applications with limited documentation
• 7+ years developing Finance-Tech solutions (payments, billing, reconciliation)
• 5+ years integrating with Tyler Technologies MUNIS or similar ERP systems
• 3+ years recent experience with Paymentus integrations (iframes, redirects, UAT/production)
• 7+ years UI/UX development with responsive design (recent experience required)
• Proven ability to work independently and deliver practical solutions

ASSYST is an Equal Opportunity Employer. Qualified applicants will receive consideration for employment without regard to race, color, religion, sex, age, disability, military status, national origin or any other characteristic protected under federal, state, or applicable local law.