U.S. Firms Embrace GenAI to Migrate, Update Mainframes

GenAI features of mainframe services reduce cost, development time in application modernization and cloud migration, ISG Provider Lens™ report says

STAMFORD, Conn.--(BUSINESS WIRE)--U.S. enterprises are adopting GenAI-based services both to migrate mainframe workloads to the cloud and to keep their legacy systems productive, according to a new research report published today by Information Services Group (ISG) (Nasdaq: III), a global AI-centered technology research and advisory firm.

The 2025 ISG Provider Lens™ Mainframe — Services and Solutions report for the U.S. and Brazil finds that GenAI is significantly changing how enterprises and service providers modernize and optimize mainframe software. Though not yet running GenAI applications on mainframes, companies are taking advantage of GenAI tools that can reduce coding costs and timelines.

“The functions that mainframes have always performed are still essential to many enterprises, and GenAI provides new ways to maximize their value,” said John Schick, ISG consulting lead on mainframe computing. “Service providers are using GenAI to open up new possibilities for clients.”

GenAI has improved application modernization techniques to the point where some U.S. companies are deciding to reengineer mainframe software rather than replatform it to the cloud, the report says. Replatforming has been popular for achieving quick savings, but GenAI is boosting demand for reengineering with more efficient code inspection, documentation and testing. Expectations for modernized software have also changed: Until 2024, most enterprises wanted providers to ensure that it behaved just like legacy applications, but now more are open to innovations that add value.

The report also examines mainframe application modernization in Brazil, where companies face many of the same challenges as their counterparts in the U.S. Demand for modernization is rising in Brazil, especially in banking, insurance and retail. Banco Itaú Unibanco, the largest retail bank in Latin America and until recently the site of the Brazil’s largest mainframe, recently announced it will complete its migration to AWS by the end of 2028.

U.S. enterprises that choose to keep their mainframes are also benefiting from GenAI through enhanced mainframe optimization services, ISG says. A growing number of companies are adopting DevOps methodologies, containers and APIs to improve their development and maintenance platforms. Many need to integrate mainframe data with the cloud and update applications to meet new security and compliance rules. Providers are using GenAI-based code inspection to accelerate the discovery of code changes and modernization of legacy code.

Most vendors of mainframe application modernization software are also adding GenAI-powered features to ease enterprise use, the report says. Though conventional large language models (LLMs) have yet to fully grasp application architecture, companies can write code faster using toolsets based on GenAI that perform functions such as assessing applications, mapping dependencies and refactoring code bases.

“GenAI is accelerating mainframe migration by reducing risk,” said Jan Erik Aase, partner and global leader, ISG Provider Lens Research. “Enterprises evaluating their mainframes’ future now have less to fear and more to gain.”

The report also explores other mainframe trends in the U.S., including the rising use of GenAI for more efficient mainframe operations and the continued growth of mainframe as a service (MFaaS) outsourcing.

For more insights into the mainframe-related challenges faced by companies in the U.S. and Brazil, plus ISG’s advice for overcoming them, see the ISG Provider Lens™ Focal Points briefing here.

The 2025 ISG Provider Lens™ Mainframe — Services and Solutions report for the U.S. and Brazil evaluates the capabilities of 54 providers across six quadrants: Mainframe Optimization Services, Application Modernization Services – U.S., Application Modernization Services – Brazil, Mainframe as a Service, Mainframe Operations and Mainframe Application Modernization Software.

The report names DXC Technology and Wipro as Leaders in five quadrants each. It names Capgemini and Kyndryl as Leaders in four quadrants each and Ensono, Infosys and TCS as Leaders in three quadrants each. Accenture, Cognizant and FNTS are named as Leaders in two quadrants each. Astadia (Amdocs), Avanade, AWS, GFT, Google, HCLTech, Heirloom Computing, Hexaware, LTIMindtree, Mphasis, NTT DATA, Rocket Software, TmaxSoft and TSRI are named as Leaders in one quadrant each.

In addition, AveriSource, Cognizant, HCLTech and Kyndryl are named as Rising Stars —companies with a “promising portfolio” and “high future potential” by ISG’s definition — in one quadrant each.

In the area of customer experience, UST is named the global ISG CX Star Performer for 2024 among mainframe service providers. UST earned the highest customer satisfaction scores in ISG's Voice of the Customer survey, part of the ISG Star of Excellence™ program, the premier quality recognition for the technology and business services industry.

Customized versions of the report are available from Astadia, AWS, FNTS, Heirloom, Hexaware, RecoveryPoint and TSRI.

The 2025 ISG Provider Lens™ Mainframe — Services and Solutions report for the U.S. and Brazil is available to subscribers or for one-time purchase on this webpage.

About ISG Provider Lens™ Research

The ISG Provider Lens™ Quadrant research series is the only service provider evaluation of its kind to combine empirical, data-driven research and market analysis with the real-world experience and observations of ISG's global advisory team. Enterprises will find a wealth of detailed data and market analysis to help guide their selection of appropriate sourcing partners, while ISG advisors use the reports to validate their own market knowledge and make recommendations to ISG's enterprise clients. The research currently covers providers offering their services globally, across Europe, as well as in the U.S., Canada, Mexico, Brazil, the U.K., France, Benelux, Germany, Switzerland, the Nordics, Australia and Singapore/Malaysia, with additional markets to be added in the future. For more information about ISG Provider Lens research, please visit this webpage.

About ISG

ISG (Nasdaq: III) is a global AI-centered technology research and advisory firm. A trusted partner to more than 900 clients, including 75 of the world’s top 100 enterprises, ISG is a long-time leader in technology and business services that is now at the forefront of leveraging AI to help organizations achieve operational excellence and faster growth. The firm, founded in 2006, is known for its proprietary market data, in-depth knowledge of provider ecosystems, and the expertise of its 1,600 professionals worldwide working together to help clients maximize the value of their technology investments.