How we make this list: we compare pricing pages, product documentation and public user reviews. Ratings come from G2, Capterra or Trustpilot, with the date we checked them.
Key takeaways
- None of the nine firms below publishes a price list. Every engagement is quoted after discovery, so a paid or free assessment is the real first step.
- Mainframe-heavy shops have the deepest bench at IBM Consulting, Kyndryl, TCS and Capgemini, each of which brings its own tooling or managed platform for COBOL, Db2 and similar workloads.
- Most large integrators now pitch AI-assisted code analysis (Cognizant Flowsource, Infosys ILEAD, TCS MasterCraft TransformPlus) to pull business rules out of old code before rewriting it.
- Small and mid-size companies with .NET, Java, Delphi or Access-era apps will usually get faster attention from ScienceSoft or Softura than from a global integrator.
- Capgemini lists a fixed four-week mainframe assessment on the Microsoft marketplace, which is one of the few clearly scoped entry points in this group.
Quick comparison
| Tool | Best for | Starting price | Free plan |
|---|
 IBM Consulting | IBM Z, OpenVMS and VME estates | See website (custom quote) | No |
 Kyndryl | Keeping a mainframe running while modernizing | See website (custom quote) | No |
 Accenture | Multi-year enterprise reinvention programs | See website (custom quote) | No |
 Tata Consultancy Services (TCS) | Tool-driven mainframe code conversion | See website (custom quote) | No |
 Cognizant | Extracting business rules from legacy code | See website (custom quote) | No |
 Infosys | Cloud migration of legacy portfolios | See website (custom quote) | No |
 Capgemini | A scoped mainframe assessment to start | See website (custom quote) | No |
 ScienceSoft | Mid-size firms modernizing custom apps | See website (custom quote) | No |
 Softura | Microsoft-stack companies in the Midwest and South | See website (custom quote) | No (free app assessment) |
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The best system integrators for legacy software
#1
IBM Consulting
Best for: IBM Z, OpenVMS and VME estates
Visit ibm.com
Starting priceSee website (custom quote)
Free planNo
If your core systems run on IBM Z, the company that builds the hardware is the obvious first call. IBM Consulting covers assessment, refactoring, hybrid cloud integration and ongoing application management, and it offers mainframe application modernization on Microsoft Azure as well as on IBM's own platforms.
The strongest signal of its legacy focus is the 2024 deal in which IBM acquired the application modernization assets of UK-based Advanced. That brought in a team with more than 30 years of mainframe work and specific experience migrating OpenVMS and VME systems, platforms many integrators simply avoid. IBM also positions those services alongside watsonx Code Assistant for Z, its generative AI tool for translating COBOL into Java.
The catch is neutrality. IBM will give you an honest technical read, but its incentives favor keeping workloads on Z or IBM software. If you want a vendor-neutral exit plan off the mainframe, get a second opinion.
What we like- Deep mainframe and Z platform knowledge
- Added Advanced's modernization team for OpenVMS and VME migrations
- Pairs services with watsonx Code Assistant for Z
Watch out for- Naturally leans toward IBM technology
- Scale and process can feel heavy for a single-application project
Starting priceSee website (custom quote)
Free planNo
Kyndryl is the infrastructure services business that spun out of IBM, and it shows. Its sweet spot is the company that cannot switch off the mainframe tomorrow but wants to stop owning one. Kyndryl zCloud is a fully managed mainframe-as-a-service offering, and Kyndryl now lists it on AWS Marketplace for clients who want to replatform or refactor in stages.
That staged approach is the real value. Kyndryl frames modernization as continuous rather than a single cutover, covering COBOL modernization, secure integration and selective migration of workloads that are ready to move. Its mainframe page also cites a Leader placement in IDC's 2025 to 2026 mainframe modernization assessment.
The honest weakness is fit for smaller buyers. Kyndryl's model is built around multi-year managed services for complex estates. If you have one aging line-of-business app on Windows servers, this is more firm than you need.
What we like- Runs mainframes as a managed service through zCloud
- Options to modernize in place or move selectively to cloud
- ZCloud also sold through AWS Marketplace
Watch out for- Infrastructure DNA means application rewrites are not its only focus
- Best suited to large, long-term contracts
Starting priceSee website (custom quote)
Free planNo
Accenture fits when legacy modernization is part of a bigger business change, such as a new operating model, an ERP replacement and a data platform all moving at once. Its application modernization practice covers replatforming, migration and mainframe work using Agile and DevSecOps methods, containerization and automated code conversion.
It has bought its way into niche legacy skills too. In 2019 it expanded its modernization capability in Japan by acquiring the core competencies of Caltec Scube, a firm focused on mission-critical legacy systems. Partnerships with AWS, MongoDB and Pega give it ready patterns for moving mainframe workloads to cloud databases and workflow platforms.
The trade-off is cost and attention. Accenture is rarely the cheapest bid, and a modest project at a mid-size company will not be its top priority. Ask who will actually staff your project and how much of the work goes offshore.
What we like- Very large delivery bench across every major cloud
- Mainframe modernization with containerization and automated code conversion
- Strong change management and industry teams
Watch out for- Premium rates
- Smaller accounts can get less senior attention
#4
Tata Consultancy Services (TCS)
Best for: Tool-driven mainframe code conversion
Visit tcs.com
Starting priceSee website (custom quote)
Free planNo
TCS is a strong pick when you have a large volume of mainframe code and want automation doing much of the heavy lifting. Its MasterCraft TransformPlus product analyzes legacy applications, recommends a strategy and automates conversion, and it is listed on the Microsoft marketplace as a mainframe modernization product.
Version 5.0 added machine learning to analyze applications and understand legacy code more accurately. For buyers, the practical benefit is better inventory and dependency mapping before anyone commits to a rewrite, which is where many legacy projects go wrong.
The weakness is the usual one for global offshore models. You need a strong internal product owner who can make fast decisions, and you should agree on overlap hours for US time zones early. Without that, automated output can pile up faster than your team can validate it.
What we like- Own patented modernization tooling (MasterCraft TransformPlus)
- Machine learning code analysis
- Global delivery scale
Watch out for- Tooling-first projects need firm scope control
- Time zone split for US teams on offshore-heavy staffing
Starting priceSee website (custom quote)
Free planNo
Cognizant's pitch is that the hardest part of legacy work is understanding what the old code actually does. Its Flowsource platform is used to decode legacy systems, and in one banking case Cognizant says it extracted and documented more than 250 business flows from legacy Java and COBOL, saving about six months of developer work.
It also points to Skygrade, which it used to rework a retailer's mainframe-based order management system, and, since May 2025, a partnership with Pegasystems that pairs its modernization services with Pega Blueprint. That combination suits insurers and banks whose legacy apps are mostly workflow and rules. Cognizant was also named a Leader in Gartner's 2026 Magic Quadrant for Custom Software Development Services.
Treat the headline numbers with care. Cost-saving and speed figures on its site come from Cognizant's own case studies, so ask for references from a client in your industry and of similar size.
What we like- Flowsource platform for business rule extraction
- Published case results on COBOL and Java estates
- Pega partnership for workflow rebuilds
Watch out for- Case metrics are vendor-reported
- Large-enterprise focus
Starting priceSee website (custom quote)
Free planNo
Infosys suits companies that want to rationalize a sprawling application portfolio and move what survives to the cloud. Its modernization offering, built on Infosys Cobalt, uses ILEAD for AI-powered reverse engineering so business logic is documented before systems are retired, rehosted or rebuilt.
The rationalization step is worth paying for. Many mid-size firms carry duplicate apps from acquisitions, and an integrator that will tell you what to switch off can save more than one that only migrates. Infosys also ties its work to AWS and Pega Blueprint, and it publishes public case studies, including a retail transaction system move to AWS.
The downside is clarity. Infosys wraps services in several platform brands, so insist on a statement of work that separates licensed tooling from labor, and confirm who owns any generated documentation when the contract ends.
What we like- Infosys Cobalt cloud services plus ILEAD AI reverse engineering
- Strong AWS ties
- Application rationalization before migration
Watch out for- Brand names (Cobalt, Topaz, ILEAD) can blur what is product versus service
- Offshore-heavy delivery
Starting priceSee website (custom quote)
Free planNo
Capgemini gives cautious buyers something rare in this market: a clearly bounded first step. Its Legacy Mainframe Modernization assessment runs four weeks and targets MIPS reduction and cost savings across COBOL, AS/400 and Db2 environments. A short, scoped engagement lets you judge the team before signing a large contract.
It is also flexible on direction. Capgemini publishes an in-place mainframe modernization approach for financial services (written alongside IBM) as well as exit options that include rehosting, rewriting and automated refactoring. That balance helps if you are still undecided about keeping the mainframe.
The weakness for US mid-market buyers is reach. Capgemini's center of gravity is large European and global enterprises. Make sure the assessment is staffed by people who will also deliver the follow-on work.
What we like- Fixed four-week mainframe assessment listed on Microsoft marketplace
- Covers COBOL, AS/400 and Db2
- Both in-place and exit strategies
Watch out for- Assessment pricing not published
- Strongest presence is in Europe and large enterprises
#8ScienceSoft
Best for: Mid-size firms modernizing custom apps4.7/5 on
G2 (4 reviews, checked Oct 2026)
Visit scnsoft.com
Starting priceSee website (custom quote)
Free planNo
ScienceSoft is the most practical option here for a company with a homegrown web or desktop app that has outgrown its original build. It offers evolution, redesign, re-engineering and cloud migration, and it partners with Microsoft, AWS, Oracle and Ispirer Systems, whose tools automate database and code migration.
What stands out for regulated buyers is compliance experience. ScienceSoft lists hands-on work with HIPAA, HITECH, PCI DSS and GDPR, and it has industry-specific modernization pages for healthcare and insurance. It also reports that more than half of its staff are senior or lead specialists, which matters on legacy code where judgment beats speed.
Be realistic about scope. ScienceSoft is a strong fit for custom business applications, portals and databases, but a large COBOL mainframe exit is better handled by the firms higher on this list.
What we like- 37 years in software engineering
- 750+ IT professionals
- Compliance experience with HIPAA, PCI DSS and GDPR
Watch out for- Not a mainframe specialist
- Smaller bench than global integrators for very large programs
#9
Softura
Best for: Microsoft-stack companies in the Midwest and South
Visit softura.com
Starting priceSee website (custom quote)
Free planNo (free app assessment)
Softura is a mid-size firm based in Farmington Hills, near Detroit, that focuses on modernizing business-critical applications. Its modernization options span re-platforming, re-hosting, re-coding, re-architecting, replacement and retirement, which is the right menu for a company still running old .NET, SharePoint or client-server apps.
The free application assessment is a sensible entry point for small and mid-size buyers who want a second opinion before budgeting. Softura also has a connected-apps framework on Microsoft Azure that puts multiple apps on a shared data pipeline with common security, useful if you plan to retire several small legacy tools at once.
The catch is stack bias. If your future platform is AWS, Google Cloud or something non-Microsoft, confirm the team's depth there before you commit.
What we like- Free application assessment
- 26+ years and over 1,000 delivered projects
- US offices in Michigan, Texas, Illinois, Indiana, Pennsylvania, Georgia and Florida
Watch out for- Heavily Microsoft and Azure oriented
- Less suited to mainframe workloads
How we chose
We started from the integrators that publish dedicated legacy and mainframe modernization practices, then checked each one against its own service pages, press releases, marketplace listings and published case studies. We looked for evidence of specific capabilities: named tooling for code analysis, platforms supported (mainframe, AS/400, OpenVMS, .NET, Java), cloud partnerships, managed-service options and how a buyer can start an engagement.
We also weighed fit for US small and mid-size companies, not just global enterprises, and looked at how each firm describes its delivery model. Public review sites such as G2, Capterra and Reddit threads are worth checking for delivery reputation before you shortlist. None of these firms publishes rates, so we did not guess at prices, and we did not run projects with them. The list reflects published information and buyer-relevant fit.
What to settle before you call an integrator
Most failed legacy projects fail before the first line of code changes. A little preparation shortens sales cycles and makes quotes comparable.
Know your modernization path
Pick a leaning among rehosting (lift and shift), replatforming, refactoring, rebuilding or replacing with SaaS. You do not need a final answer, but a preference tells the integrator which team to send. Mainframe exits, for example, need different people than a .NET upgrade.
Inventory what you have
List applications, languages, databases, interfaces, batch jobs and who still understands each one. Integrators will price risk into any unknowns, so a rough inventory lowers the quote. If you have none, pay for a scoped assessment first, like Capgemini's four-week offer or Softura's free review.
Ask the contract questions early
- Is the work fixed price, time and materials, or a managed service with a multi-year term?
- What share of the team is onshore, and what are the overlap hours with your time zone?
- Who owns code, documentation and any AI-extracted business rules at the end?
- Is any proprietary conversion tool licensed separately, and do you need it after go-live?
- How is data migration validated, and what is the rollback plan?
Match the firm to the size of the job
A global integrator will deliver a mainframe exit with thousands of programs. It may not prioritize a single 15-year-old order app. For smaller scopes, mid-size firms often put senior people on the account and move faster. Ask every bidder for a reference client of similar size.
Frequently asked questions
What does a system integrator do for legacy software?
A system integrator assesses your old applications, picks a modernization path and then does the work, which can include code conversion, data migration, cloud setup and connecting the new system to everything else you run. Many also offer ongoing application management after go-live.
How much does legacy modernization cost?
None of the firms on this list publishes pricing, because cost depends on code volume, languages, data, integrations and the chosen path. Expect a discovery or assessment phase first. Use that phase to get a scoped estimate before committing to the full program.
Should a mid-size company hire a global integrator?
Only if the job is large or tied to a mainframe. Global firms bring deep tooling and staff, but smaller projects can get less senior attention. Mid-size firms such as ScienceSoft and Softura are often a better match for single applications or small portfolios.
Can AI convert COBOL to Java automatically?
Partly. Tools like IBM watsonx Code Assistant for Z, TCS MasterCraft TransformPlus and Cognizant Flowsource speed up code analysis and conversion. People still need to test the result, check business rules and fix edge cases, so plan for human review.
Do I have to leave the mainframe to modernize?
No. Kyndryl, IBM and Capgemini all offer in-place modernization, such as adding APIs, DevOps tooling or moving to a managed mainframe service. Many companies move only the workloads that are ready and keep the rest where they are.
How long does a legacy modernization project take?
A focused assessment can take a few weeks, while a single-application rebuild often runs several months. Large mainframe programs can span years and are usually delivered in phases so the business keeps running throughout.
Sources we checked (18)
- https://www.ibm.com/consulting
- https://www.infoworld.com/article/2335872/ibm-to-acquire-application-modernization-assets-from-advanced.html
- https://www.kyndryl.com/us/en/services/core-enterprise-zcloud
- https://aws.amazon.com/marketplace/pp/prodview-6f267ppbbtmgi
- https://www.accenture.com/en/services/cloud/application-transformation/application-modernization
- https://newsroom.accenture.com/news/2019/accenture-expands-capabilities-for-modernizing-legacy-systems-in-japan-through-agreement-with-caltec-scube
- https://www.tcs.com/who-we-are/newsroom/press-release/new-release-mastercraft-transformplus-5-0-ml-legacy-application-modernization
- https://marketplace.microsoft.com/en-us/product/tcs-india1583226661510.mastercraft_transformplus_mainframe_modernization?tab=Overview&exp=ubp8
- https://www.cognizant.com/us/en/services/application-services
- https://www.cognizant.com/us/en/services/ai/ai-modernization
- https://news.cognizant.com/2025-05-22-Cognizant-and-Pegasystems-Partner-to-Bring-AI-led-Transformation-to-Enterprise-Legacy-Modernization
- https://www.infosys.com/services/digital-process-automation/offerings/modernization-solution.html
- https://www.infosys.com/services/cloud-cobalt/case-studies/cobalt-stories.html
- https://marketplace.microsoft.com/en-us/marketplace/consulting-services/capgemini-group.legacy_modernization
- https://www.capgemini.com/us-en/insights/research-library/mainframe-modernization-patterns-for-financial-services/
- https://www.scnsoft.com/application/modernization
- https://www.softura.com/application-modernization-solutions/
- https://marketplace.microsoft.com/en-us/product/softurainc.softura_application_modernization_services?tab=overview
Is your product missing or out of date?
We review this list regularly. Vendors can request a listing, send updated pricing or ask about featured placement.
Shihab Mia · Founder, Rankite
Shihab has 5+ years in B2B and SaaS SEO. He writes Rankite's software buying guides from pricing pages, documentation and public user reviews. More about Shihab.