Sr. Application Developer - Legacy System Modernization

Cass Information Systems · Bridgeton, Missouri, United States

Location

Bridgeton

Job Type

Full Time

Posted

July 04, 2026

Job Description

The Senior Application Developer – Legacy Modernization strengthens and evolves legacy systems by improving operational stability, enhancing observability, and migrating core services to modern, scalable platforms. This role designs and executes modernization strategies, establishes engineering standards, and leverages automation, CI/CD, and AI-assisted development tools to accelerate system transformation. It balances innovation with business continuity by improving system reliability, enabling efficient incident response, and managing technical risk across both legacy and modern environments.
PRINCIPAL RESPONSIBILITIES AND DUTIES:
Designs, develops, and implements the incremental migration of legacy application logic to C# / .Net, establishing scalable patterns, reusable components, and engineering standards.

Evaluates existing batch and online processes for modernization readiness and defines migration strategies that balance technical risk, cost,...
        

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