- Amanda Mahoney
- June 25, 2025
Revolutionizing Mainframe Modernization: How We Transform Legacy Systems with AWS and AI

For many organizations, especially in the US government, dealing with outdated legacy mainframe systems is a significant challenge. These systems, often decades old and written in languages like COBOL, are mission-critical but have become costly, difficult to maintain, and hard to update. Compounding this issue is a dwindling workforce with the specialized knowledge to manage these older technologies, alongside missing or outdated documentation, making modernization a complex, high-risk, and high-cost endeavor. Now a new case study from the Karsun Solutions ReDuX team and Amazon Web Services (AWS) sheds light on this enduring old challenge.
Navigating The Mainframe Modernization Maze
Before the ReDuX team stepped in with their innovative approach, understanding intricate legacy systems was a monumental task. It involved manually examining tens of thousands of lines of code to grasp their functionality and business logic. This manual process could take months, making the path to modernization slow and fraught with potential errors, especially given the systems’ vast functionality and integration with other complex environments.
A Game-Changing Solution: ReDuX Platform
Karsun Solutions, an AWS Partner specializing in US government clients, recognized this opportunity to provide modernization and efficiency. Leveraging their deep expertise, they developed ReDuX, powered by Amazon Bedrock, a fully managed service that offers high-performing foundation models for building generative AI applications.
The core goal of ReDuX is to “open the closed box” of legacy systems, providing crucial insights into their behavior so that optimization and modernization can happen simultaneously. ReDuX also plays a vital role in code generation, converting legacy code into modern equivalents compatible with cloud-native applications.
Leveraging Agentic AI, key components of ReDuX include:
- Blueprint Agents: Offers deep insights into existing systems and maps them to new services.
- Transformation Agents: Generative AI agents that utilizes Blueprint agents to create new code, assist with incremental migration, enhance security and privacy, and even overcome common issues like hallucinations that can occur with large language models (LLMs). It also provides prompt templates to save developers time.
Transformative Results and a New Business Frontier
In short, the impact of ReDuX on Karsun’s operations has been nothing short of revolutionary. Using this toolkit has delivered impressive benefits, including:
- 4 times faster project delivery.
- 50% fewer resources required for migration projects.
- A 22.5% increase in productivity for project teams.
- A 2 times improvement in code quality, as evidenced by a better error rate in quality control tests after conversion.
ReDuX now allows modernization teams to “get a good look into things quickly and start planning faster and implementing better”. -Judewin Gabriel, Lead Cloud Architect
Ready to Accelerate Your Modernization Journey?
ReDuX’s pioneering work using AI and AWS demonstrates a powerful fraemwork for tackling complex legacy system modernization. If your organization is navigating the challenges of moving from mainframes to modern cloud environments, this success story offers a compelling vision for what’s possible. Connect with us to learn more.
2X
Reduced Effort