OpenLegacy Gives AWS Customers a Way to Modernize the Mainframe Without Shutting It Off
AWS has built OpenLegacy directly into AWS Transform for Modernization, its service for updating legacy systems. The addition targets a problem that has quietly stalled mainframe modernization projects for years: how to move workloads to the cloud without breaking the connections those workloads still need to the mainframe systems left behind
Most modernization efforts run into the same wall. Enterprises want off the mainframe, but a full, one-time cutover means gambling core operations on a single event. OpenLegacy's technology, now embedded in the AWS Transform for Modernization workflow, gives customers a way around that: migrate one workload, keep it talking to the mainframe, then move the next one.
The mechanism is straightforward. When a migration reaches the decomposition stage, where legacy applications are broken apart and rebuilt for the cloud, OpenLegacy automatically generates integration bridges and API facades that link the new cloud environment back to the mainframe. No separate toolset, no added step for migration teams. It runs inside the AWS Transform environment itself.
That matters most for organizations that can't afford downtime or data gaps while they modernize, which is why the integration is aimed at financial services, insurance, and telecommunications. These are industries where core systems, transaction processing, policy administration, and billing often still run on mainframe infrastructure that has to stay operational for months or years while migration proceeds around it.
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New AWS integration from OpenLegacy lets businesses modernize in stages, keeping legacy and cloud systems connected
(OpenLegacy)
"Recovering the business logic in legacy code is the hard part of modernization, and doing it at machine speed is what lets customers modernize one workload at a time instead of all at once," said Omri Kessel, AWS General Manager, Agentic AI Modernization. "The AWS Transform for Modernization composability framework lets us bring in the right capability for each phase, and OpenLegacy is a great example: it keeps each workload we move to AWS communicating with the mainframe behind it, so customers modernize incrementally, in months, instead of betting the business on a big-bang cutover."
The integration fits into a larger AWS strategy of building out a composable modernization toolchain, where specialized partners handle distinct phases of the migration lifecycle rather than AWS trying to solve every technical problem itself. Assessment, documentation, transformation, testing, and deployment each draw on different tools within that framework. OpenLegacy's piece of it is narrow but critical: keeping the old and new environments in sync while the migration is underway.
Ron Rabinowitz, CEO of OpenLegacy, identifies coexistence between legacy and modern systems as the primary factor determining the success of modernization projects. "Mainframe modernization succeeds when the old and the new can work together," he stated. "By embedding OpenLegacy into AWS Transform for Modernization, organizations can bridge legacy systems and cloud-native environments through a coexistence model, enabling phased modernization of individual business processes."
This perspective reflects a broader shift within enterprise IT. Large-scale, single-event replacement programs are increasingly avoided, not due to technological limitations, but because the operational and financial risks associated with a single cutover are often unacceptable for organizations managing mission-critical systems. Incremental migration, in which teams modernize individual processes while maintaining ongoing operations, has become the preferred approach for CIOs and CTOs accountable to boards and risk committees.
For OpenLegacy, the AWS integration expands a partnership grounded in its Mainframe Modernization certification within the AWS Partner Network and a customer base that includes tier-1 financial institutions, insurers, and government agencies. Direct integration with AWS Transform for Modernization provides a more seamless adoption pathway for enterprises considering cloud migration, eliminating the need for customers to assess and onboard an additional vendor.
