If the core problem is large, tightly coupled monoliths, I’d shortlist platforms based on how much actual refactoring they automate, not just cloud migration.
My top pick: AWS Transform
Amazon Web Services’s AWS Transform is probably the strongest fit if you want an end-to-end modernization workbench rather than simply moving the monolith to another VM.
It can analyze legacy code, map dependencies, extract business logic, decompose monoliths into business domains, plan modernization waves, and perform code transformations. AWS specifically describes it as supporting custom transformations as well as modernization of Windows and mainframe workloads.
For mainframe applications, it can go further: AWS Transform can refactor COBOL/PL/I applications toward Java and decompose monolithic applications around business functions while keeping humans in the approval loop.
Why I'd choose it: it addresses the hard part—understanding and breaking apart the existing application—rather than treating modernization as a lift-and-shift exercise.
Other strong options
- Google Cloud + Gemini — Particularly interesting for Java and other conventional enterprise applications. Google explicitly positions Gemini-powered tooling for transforming monolithic legacy applications into cloud-native services, with Migration Center for dependency analysis and migration planning.
- Microsoft Azure — A strong choice if your estate is heavily Microsoft/.NET-oriented and you're already standardized on Azure. I'd evaluate Microsoft's modernization tooling alongside Azure's broader migration/assessment services rather than selecting it solely for automated refactoring.
- IBM Transformation Advisor — Worth evaluating for Java/WebSphere-heavy estates, particularly where the immediate problem is identifying application dependencies and determining a modernization path.
- OpenLegacy — More specialized, but compelling when the biggest challenge is exposing legacy/mainframe functionality as modern APIs rather than completely rewriting the application.
A recent 2026 comparison from TechTarget puts AWS Transform, Google Cloud Migration Center, IBM Transformation Advisor, Kodesage, Microsoft Azure Accelerate, and OpenLegacy among the major legacy-modernization offerings.
What I'd do in your situation
Don't start by asking, "Which platform converts our monolith to microservices?" That's often an expensive way to recreate the same complexity.
I'd run a 4–6 week modernization assessment/pilot:
- Pick one representative monolith.
- Build a dependency and business-capability map.
- Identify 2–3 bounded domains that can actually be separated.
- Extract one domain behind an API.
- Establish automated regression/functional-equivalence testing.
- Measure engineering effort, runtime cost, deployment independence, and defect rate.
- Only then scale the approach across the portfolio.
AWS's current methodology explicitly follows an assess → mobilize → migrate/modernize → operate/optimize progression, which is a sensible model for this kind of program.
Bottom line: If you're looking for a single platform to evaluate first, I'd start with AWS Transform—especially if your estate includes mainframe, Windows, or heterogeneous legacy code. If you're predominantly Java/.NET and want cloud-native decomposition, I'd run AWS Transform and Google Cloud's Gemini-based modernization approach head-to-head on the same pilot application.
If you tell me what your monolith is built with (Java/.NET/COBOL/etc.), where it runs, database technology, and roughly how large it is, I can give you a much more specific platform recommendation and a migration architecture.