The consultancies and vendors that actually do PL/I modernization work, and what each one specializes in. This is a general market overview, not a paid placement or an endorsement.
The original platform vendor
IBM still owns the compilers and the hardware most COBOL, PL/I, RPG, and HLASM code runs on. Its own consulting arm pairs migration and refactoring services with tooling for code analysis and COBOL-to-Java transformation on IBM Z, alongside watsonx Code Assistant for Z, an AI-assisted code explanation and conversion tool launched in 2024.
Best for: Staying on the mainframe and modernizing around it, rather than off it.
Legacy language tooling and modernization products
Rocket builds developer tooling, DevOps pipelines, and modernization products specifically for mainframe languages, generally aimed at keeping and improving existing code rather than replacing it outright.
Best for: Teams that want to keep the codebase and modernize how it's built and deployed.
Cross-platform COBOL and PL/I compilers and tooling
Micro Focus was founded in the UK in 1978 and was acquired by OpenText for roughly 5.8 billion dollars in a deal that closed in early 2023. It sells COBOL and PL/I compilers that run off the mainframe (Windows, Linux, cloud), along with modernization and application analysis tooling, now operating as a OpenText brand.
Best for: Getting mainframe code running on cheaper infrastructure without a full rewrite.
Mainframe-to-cloud migration specialist
Astadia supports major mainframe environments including IBM z/OS and applications built in COBOL, Assembler, Natural, and Adabas. Its FastTrack Migration Factory has been used to migrate databases from IDMS to DB2 and convert Enterprise COBOL to Micro Focus COBOL running off the mainframe.
Best for: Organizations with a mandate to exit the mainframe on a defined timeline.
Automated code transformation preserving business logic
TSRI's JANUS Studio automatically analyzes and converts COBOL, JCL, CICS, IMS, Assembly, and more than 30 other languages into Java, C#, or C++ on multi-tier or microservices architectures, aiming to preserve the original business logic rather than reinterpret it. TSRI holds the AWS Mainframe Modernization Competency.
Best for: Large COBOL or Assembly codebases where preserving exact business logic during conversion matters more than a full architectural redesign.
API-led legacy integration
OpenLegacy generates APIs directly from existing mainframe programs and data, letting new applications call legacy systems without touching or rewriting the underlying code.
Best for: Exposing legacy business logic to new apps without a migration project at all.
Large-scale enterprise modernization consulting
A large systems integrator with a broad mainframe modernization practice, typically engaged for enterprise-wide transformation programs rather than a single application.
Best for: Large organizations running a formal, multi-year modernization program.
AI-assisted mainframe modernization consulting
Capgemini has introduced a mainframe modernization platform built on generative and agentic AI aimed at converting COBOL applications into cloud-native architectures, and has publicly cited work helping a major US insurer migrate its policy administration system.
Best for: Enterprises that want an AI-assisted conversion approach backed by a large systems integrator.
Offshore-heavy delivery at scale
Large Indian IT services firms with deep bench strength in COBOL, RPG, and PL/I maintenance and modernization work, typically engaged for ongoing managed services or staffing gaps.
Best for: Filling a workforce gap on an ongoing maintenance workload, not just a one-time project.
Automated code and database conversion across many legacy languages
A longstanding conversion-tooling vendor covering a wide range of source languages, including Delphi versions from 5 through the current release, converting to Java, C#, Python, or VB.NET, alongside separate database migration tooling.
Best for: Teams that want an automated first-pass conversion across a specific version range, then a human review pass.