Sr. Application Developer - Legacy System Modernization
Cass Information Systems
·Jun 15, 2026
- Location
- Bridgeton, MO
- Workplace
- Onsite
- Type
- Full-time
- Department
- IT
- Seniority
- Senior
- Industry
- Technology
- Category
- Engineering
- Role type
- Individual Contributor
- Environment
- Office
- Source
- UKG
Overview
The Senior Application Developer focuses on modernizing legacy systems by improving operational stability and migrating core services to scalable platforms. You'll design and execute modernization strategies, establish engineering standards, and leverage automation and AI tools. Responsibilities include developing in C#/.NET, establishing CI/CD pipelines, conducting code reviews, troubleshooting issues, and enhancing system observability. The role requires expert-level C# and .NET skills, experience with microservices architectures, and knowledge of relational databases and AI-assisted development environments.
Skills
C#.NetGitHub ActionsAzure DevOpsAI-assisted development tools
