Freelance Full Stack Web Developer Jobs in Wisconsin

Join J. J. Keller as a Software Engineer and help build innovative, customer-facing web applications that support critical business operations and deliver exceptional user experiences. In this role, you'll work across the full technology stack, designing, developing, testing, and supporting modern applications using Modern Web Technologies, .NET/C#, RESTful APIs, and SQL Server.

We're looking for a collaborative software engineer who enjoys solving complex technical challenges, delivering high-quality code, and leveraging AI-assisted development tools such as GitHub Copilot to improve efficiency, software quality, and innovation. You'll contribute to the full Software Development Life Cycle (SDLC), from requirements analysis and solution design through development, testing, deployment, and ongoing support. You’ll lead small to mid-sized projects, create scalable and secure solutions, champion best practices, and partner with cross-functional teams to enhance existing applications and develop new capabilities.

This is great opportunity for a developer who is passionate about full-stack software engineering, cloud-ready application development, API integrations, secure coding practices, artificial intelligence in software development, and continuous learning.

If you're excited about building modern software, applying emerging technologies, and making a meaningful impact within a collaborative and growth-oriented environment, apply today!

Key Technologies: Modern Web Technologies, React, ASP.NET MVC, .NET/C#, SQL Server, REST APIs, SDLC, GitHub Copilot, AI-Assisted Development, OWASP Security Practices, Full-Stack Development, Application Integration.

• Develops and maintains full-stack web applications using Modern Web Technologies, asp.net MVC, .NET/C#, RESTful APIs, and SQL Server.
• Develops and supports complex backend services, business logic, system integrations, and APIs using .NET and C#.
• Uses approved AI-assisted development tools, including coding assistants, throughout the SDLC to support requirements analysis, solution design, code development, testing, documentation, troubleshooting, and code review.
• Reviews and validates AI-generated output to ensure code quality, security, maintainability, accuracy, and compliance with organizational development standards.
• Identifies opportunities to use AI and automation to improve developer productivity, software quality, testing coverage, and delivery efficiency.
• Performs assigned programming tasks related to new development or maintenance on assigned websites or applications.
• Analyzes user needs and impact to other site areas to determine technical requirements of assigned tasks.
• Promotes strong quality practices by performing unit testing and providing appropriate level of support for user acceptance testing, as needed.
• Follows secure coding standards and incorporates basic security-by-design principles into assigned development tasks.
• Adheres to OWASP best practices to reduce common security risks such as input validation errors, insecure data handling, etc.
• Maintains accurate technical documentation for assigned programming projects.
• Acts as a support resource for the technical support staff to ensure that customer-reported issues are being addressed in an efficient and accurate manner.
• Performs lead developer role on assigned projects.
• Interfaces with Website and Database Administrators to maintain optimal server configuration, database accuracy/integrity and for coordination of staging and production moves.
• Develops and maintains a solid understanding of the technology tools and trends and remains current in new technology developments and their potential impact on the department.

Education

• Associate's degree in a Computer Science or technology-related field.  Bachelor's Degree preferred.
• In lieu of degree, may consider a combination of education and related work experience.

Experience

• 3+ years software or web development experience including analysis, technical design, coding and testing.
• Working knowledge of the Software Development Life Cycle (SDLC).
• Object oriented programming experience.
• Understanding of SQL Server development and database structures.
• Experience developing full-stack web applications using Modern Web Technologies and .NET/C#.
• Experience building and consuming RESTful APIs and integrating frontend applications with backend services.
• Experience using AI-assisted software-development tools, such as GitHub Copilot or comparable technologies, within the SDLC.
• Demonstrated ability to evaluate, test, and refine AI-generated code rather than relying on generated output without developer review.
• Understanding of secure full-stack development practices, including authentication, authorization, input validation, API security, and protection of sensitive data.

Internal J. J. Keller experience requirements may vary from those for external candidates, with consideration given to demonstrated performance, institutional knowledge, and career progression within the organization.

Work is performed primarily in a standard office environment. Work involves operation of personal computer equipment for extended periods of time. Occasional travel to offsite offices, customer sites and/or industry and training events may also be required, depending on assignment.