Legacy applications eat up budget, leaving less room for new initiatives. Yet replacing an aging system isn’t automatically the right move, introducing more risk than older technology. The solution is to find an application modernization partner that understands both the existing system and the business specifics.
Vendors are different. Some specialize in large-scale enterprise transformation, others supply automated tools, and specialized engineering partners focus on individual business-critical engagements.
This guide compares 10 application modernization companies and solutions in 2026 for the US market, grouped by their delivery approach. You’ll find their capabilities, relevant use cases, limitations, and practical criteria for choosing between them. Read this editorially curated shortlist below.
Application Modernization Companies at a Glance
The table below compares 10 application modernization companies by major criteria that influence delivery. Use it to identify which providers best match your technical requirements, project scope, and business priorities. Read the full approach at our application modernization strategy guide.
| Vendor | Category | Best for | Legacy stacks covered | Modernization approach | Cloud alignment | Engagement model |
| Accenture | Global SI | Complex enterprise transformations | COBOL, mainframe, Java, .NET, enterprise platforms | Rehost to rebuild | AWS, Azure, GCP | Enterprise programs, managed services |
| IBM Consulting | Global SI | Mainframe and hybrid-cloud modernization | IBM Z, COBOL, Java, enterprise workloads | Optimize, refactor, replatform | IBM Cloud, AWS, Azure | Consulting, implementation, managed services |
| Kyndryl | Global SI | Mission-critical legacy infrastructure | Mainframe, IBM Z, enterprise applications | Rehost, replatform, refactor | AWS, Azure, GCP | Transformation programs, managed services |
| Capgemini | Global SI | Enterprise application portfolio modernization | Mainframe, Java, .NET, enterprise applications | Rehost to rebuild | AWS, Azure, GCP | Enterprise consulting and delivery |
| CAST | Automation platform | Application discovery and dependency analysis | Java, .NET, COBOL and other supported languages | Assessment, refactoring intelligence | AWS, Azure, GCP | Software licensing, partner-assisted services |
| AWS Transform for mainframe | Automation platform | Mainframe modernization on AWS | COBOL and supported mainframe assets | Automated refactoring, replatforming, reimagining | AWS | Cloud service, partner-led delivery |
| Mechanical Orchard | Modernization specialist and platform | Incremental replacement of critical legacy systems | Mainframe and other legacy systems, subject to assessment | Incremental reengineering and replacement | AWS | Project-based engineering and platform-enabled delivery |
| SoftServe | Engineering partner | Cloud-native modernization and SaaS transformation | .NET, Java, legacy web applications | Replatform, refactor, rearchitect | AWS, Azure, GCP | Dedicated teams, project delivery |
| Endava | Engineering partner | Financial platforms and complex business applications | Java, .NET, monolithic applications, other legacy technologies | Refactor, rearchitect, rebuild | AWS, Azure, GCP | Engineering squads, consulting, project delivery |
| Devox Software | Engineering partner | Mid-market legacy modernization and phased migration | .NET Framework, Java, PHP, legacy web applications | Replatform, refactor, rearchitect, selective rebuild | AWS, Azure, GCP, cloud and hybrid environments | Improved discovery, dedicated teams, phased projects |
We pointed out stack coverage as publicly described as of October, 2026. We do not guarantee that every vendor supports every version. Confirm these details during procurement.
How We Assessed Application Modernization Companies for This List
Earlier, we reviewed top legacy modernization companies in the US. Application modernization companies differ, almost at everything: approaches, specialization, experience, and so on. A global systems integrator managing hundreds of applications may be unsuitable for replacing one ERP module.
Likewise, a powerful code analysis platform cannot independently take responsibility for business requirements ERP legacy modernization built from scratch. That’s why we organized the shortlist around the following evaluations:
- Legacy Stack Coverage. Providers must understand the technologies already running your business. For some organizations, that means COBOL, PL/I, IBM mainframes, and decades-old batch processing. For others, the challenge is .NET Framework, Java EE, VB6, Delphi, Oracle Forms, or monolithic PHP applications. Ask for modernization examples based on your specific technology and integration patterns to make sure the fitting.
- Range of Modernization Approaches. A credible partner is technology- (and approach-) agnostic. It selects the appropriate modernization strategy for the client whether it’s incremental modernization or not, rehosting, replatforming, refactoring, rearchitecting, or rebuilding, finding the best fit. The choice depends on business value, system condition, technical dependencies, and acceptable operational risk.
- Risk and Business Continuity Control. Application modernization is particularly sensitive when systems process payments, warehouse orders, insurance claims, manufacturing operations, or other business-critical transactions. Ask how the vendor handles failed cutovers, inconsistent data, and integrations that cannot be interrupted.
- Automation and AI-Assisted Modernization. AI accelerates work; however, generated code still needs validation against functional requirements. Ask for a demonstration based on a representative part of your codebase.
- Cloud and Platform Alignment. AWS, Microsoft Azure, and Google Cloud provide different modernization tools, services, and architectural options. Buyers should distinguish between general cloud delivery experience, official partner tiers, verified competencies, and individual engineering certifications. Verify the partner’s current official cloud directory listing and completed projects on your preferred platform.
- Proven Outcomes and Cost Transparency. In the case studies, look for measurable evidence such as reduced infrastructure costs, shorter release cycles, improved reliability, faster deployment, or lower maintenance effort.
As a source base for the shortlist, we used publicly available service descriptions, customer reviews, and modernization case studies, to pinpoint the differences in delivery models and target customers.
Additionally, we excluded options that lacked sufficiently relevant public modernization evidence for this comparison. Devox Software appears in the specialist engineering category because this is not an independent research-firm ranking. We pre-vetted the companies and grouped them by delivery approach rather than assigned numerical quality scores. This is what we’ve got.
Global Systems Integrators
Global systems integrators (SIs) best serve large enterprises while they undergo complex modernization programs. They offer combined strategic consulting, architecture, engineering, systems integration, cloud transformation, and long-term application management, so the client gets covered from all sides.
Their main advantage is organizational scale. This way, they coordinate large portfolios and multiple technology vendors under one transformation program. However, their delivery and commercial structures may be more extensive than necessary for modernizing one application or one mid-size company.
Accenture
Headquarters: Dublin, Ireland
Target segment: Large enterprises, multinational organizations, and government agencies
Accenture modernizes enterprise applications in all respects: cloud migration, legacy architecture transformation, application development, DevSecOps, and mainframe modernization. They deliver holistic, foundational changes involving infrastructure, data, business processes, and operational models. The company works with AWS, Microsoft, Google Cloud, and other enterprise technology providers.
Best fit when: You need enterprise-wide application modernization services managing multiple modernization workstreams simultaneously. However, if your scope is limited to one app with fewer governance layers, consider a smaller, directly managed engineering team.
IBM Consulting
Headquarters: Armonk, New York, USA
Target segment: Large enterprises, particularly those with IBM infrastructure and mainframe environments
IBM Consulting preserves the value of existing mainframe investments. Its services combine application assessment, legacy code modernization, hybrid-cloud architecture, API integration, and enterprise application transformation.
IBM’s WatsonX Code Assistant for Z supports analyzing COBOL applications, understanding dependencies, and assisting with Java transformation. This makes IBM particularly relevant to companies that must modernize mainframe software without immediately abandoning the platform.
Best fit when: Your organization operates substantial IBM Z workloads, relies on COBOL applications, or requires mainframe and cloud environments to coexist.
Kyndryl
Headquarters: New York, USA
Target segment: Large enterprises with mission-critical infrastructure and legacy applications
Kyndryl manages and transforms complex enterprise technology environments through discovery, portfolio assessment, migration planning, rehosting, replatforming, refactoring, and cloud integration. Kyndryl’s approach is particularly relevant when the application can’t be separated easily from the infrastructure that supports it.
Best fit when: You need software modernization services for mission-critical applications while also transforming the underlying infrastructure. But consider alternatives if you want a standalone product engineering partner focused primarily on application code.
Capgemini
Headquarters: Paris, France
Target segment: Large enterprises and organizations with complex application portfolios
Capgemini modernizes apps spanning legacy assessment, cloud adoption, architecture transformation, software engineering, and application portfolio optimization. The company also provides AI-assisted modernization to extract business rules and documentation from older applications.
Best fit when: Contact Capgemini if you need portfolio-level assessment and architecture consulting.
Modernization Platforms and Automation Vendors
Modernization platforms best benefit due to specialized tools they offer to understand, analyze, refactor, or replace legacy applications. Unlike full-service engineering consultancies, modernization platforms primarily accelerate specific technical activities. A platform can significantly reduce manual effort, but buyers must still establish who owns the decisions and infrastructure.
CAST
Headquarters: New York, USA
Target segment: Mid-market and enterprise organizations with complex application portfolios
CAST develops software intelligence tools that analyze application structure, dependencies, code health, technical debt, and cloud readiness. Its main products include CAST Highlight and CAST Imaging to understand apps before deciding how to modernize them, which is particularly valuable for undocumented monoliths where important business logic may be distributed across application code.
Best fit when: You need reliable application discovery and dependency mapping before committing to a modernization strategy. However, for full contractual responsibility, consider alternatives.
AWS Transform for Mainframe
Provider: Amazon Web Services
Target segment: Organizations modernizing supported mainframe workloads with an AWS-oriented target architecture
AWS Transform for mainframe modernizes legacy mainframe applications with AI. The service supports activities such as analyzing source code, generating technical documentation, extracting business logic, planning modernization waves, and transforming supported COBOL applications into Java.
Its main advantage is reducing repetitive analysis and translation work, particularly for organizations with large codebases. However, code conversion does not automatically establish functional equivalence. Teams still need to validate results: batch processing, database behavior, integrations, performance, and operational controls.
Best fit when: Your organization has supported COBOL mainframe workloads and is evaluating modernization toward AWS.
Mechanical Orchard
Headquarters: San Francisco, California, USA
Target segment: Organizations with business-critical legacy systems requiring careful replacement
Mechanical Orchard focuses on incremental reengineering and replacement. Rather than treating modernization as a straightforward code conversion exercise, the company emphasizes how existing applications behave and preserving that behavior while introducing modern technology.
Best fit when: Mechanical Orchard is particularly relevant where legacy applications contain undocumented business rules that have accumulated over many years.
Specialist Engineering and Delivery Partners
Delivery partners serve mid-market and enterprise teams that need experienced engineering teams to modernize specific applications, platforms, or services without establishing a large transformation program. They are particularly relevant for companies working with outdated .NET applications, Java monoliths, legacy web platforms, complex databases, or aging business systems.
SoftServe
Headquarters: Austin, Texas, USA
Target segment: Mid-market and enterprise organizations
SoftServe modernizes apps, offers cloud transformation, software engineering, platform development, and DevOps services. The company works across major cloud ecosystems and has developed modernization accelerators, including the SoftServe Application Modernization Platform.
Best fit: You need cloud-native engineering, application refactoring, and modernization accelerators within an established delivery organization.
Endava
Headquarters: London, United Kingdom
Target segment: Mid-market and large enterprises
Endava provides software engineering, cloud transformation, application modernization, and digital platform development. Endava’s approach covers technical assessment, architecture modernization, application redevelopment, API integration, and migration from monolithic environments toward more modular systems.
Best fit when: Your legacy system modernization project involves financial transactions or complicated integrations. However, consider alternatives if you need a dedicated mainframe code-conversion platform or an infrastructure-first transformation provider.
Devox Software
Headquarters: Miami, Florida, USA
Target segment: Mid-market companies and enterprises modernizing business-critical applications
Devox Software offers legacy modernization services through architecture assessment, targeted refactoring, technology upgrades, cloud migration, and incremental redevelopment. We focus on preserving business-critical functionality while reducing the technical limitations that slow down software delivery.
Our specialty is that we use AI-assisted code analysis and engineering automation due to our AI Solution Accelerator™ pipeline, where they can improve discovery, dependency mapping, documentation, and test coverage.
However, architectural decisions and functional validation remain engineering responsibilities. We’ve included ourselves in this list because we believe our AI-accelerated, incremental legacy modernization delivery model fits the criteria above.
Best fit when: You need application modernization services for one or several critical applications, retain control over architecture and source code, and deliver changes incrementally without committing to an enterprise-wide rewrite.
How to Choose the Right Application Modernization Partner
An enterprise retiring a mainframe estate faces different risks from a SaaS provider upgrading a legacy .NET Framework application. The size of the software portfolio, operational criticality, available engineering capacity, and expected business value should determine the type of partner you consider. Here’s also what you need to consider.
Red Flags When Evaluating Modernization Vendors
Watch for these warning signs before signing a contract:
- A complete rewrite quote without technical discovery. Complex legacy applications often contain undocumented rules and dependencies.
- A lift-and-shift-only proposal. Rehosting may be appropriate, but it does not necessarily resolve application-level technical debt.
- No documented rollback strategy. This is especially concerning for transaction-heavy or operationally critical systems.
- Black-box automated code conversion. Transformation tools should provide inspectable outputs, test evidence, and clear ownership terms.
- Unverifiable success claims. Ask for specific project scope, baseline metrics, and measurable outcomes.
- No knowledge transfer plan. Your internal team should understand the modernized architecture and ongoing support requirements.
A reliable partner should be able to explain not only how it will modernize the system, but also which components it recommends leaving unchanged.
For questions helping to choose an application modernization vendor, download a shortlist.
What Does Application Modernization Cost in 2026?
Application modernization costs vary significantly depending on the circumstances. Rehosting an application may require relatively little code modification, while full rebuilding involves recreating business functionality, testing it against existing behavior, and moving users and data to the replacement system. For this reason, modernization costs should be compared by scope rather than by a single industry-wide average.
Cost Drivers by Modernization Approach
| Approach | Typical relative effort | Main cost drivers | Best suited for |
| Rehost | Lower | Infrastructure configuration, compatibility, migration testing | Moving workloads without major functional changes |
| Replatform | Low to medium | Runtime upgrades, dependencies, databases, deployment changes | Reducing platform risk while preserving existing logic |
| Refactor | Medium | Code complexity, automated tests, coupling, maintainability issues | Improving an application’s internals without changing its business behavior |
| Re-architect | Medium to high | Service boundaries, data ownership, integrations, observability | Removing architectural bottlenecks and enabling independent deployments |
| Rebuild | High | Functional discovery, new development, testing, data migration, parallel operation | Replacing software whose architecture is no longer economically viable |
These are relative effort categories, not vendor quotations or statistically derived market price bands. The primary cost factors include:
- Codebase size and complexity: Millions of lines of code may require automated analysis and extensive regression testing.
- Integration count: Connections to ERPs, payment gateways, databases, third-party APIs, and internal services increase coordination and testing effort.
- Data migration: Historical records, incompatible schemas, and strict consistency requirements can materially increase costs.
- Business continuity: Parallel operation, reversible releases, and zero-interruption requirements may require additional infrastructure and engineering.
- Compliance and security: Regulated systems require formal evidence, audit trails, security testing, and additional approvals.
- Documentation and test coverage: Poorly documented applications often require more discovery and characterization testing before meaningful changes appear.
For meaningful comparisons, ask all vendors to estimate the same scope, include the same deliverables, and state their assumptions about cloud expenses, testing, data migration, and post-release support.
Conclusion: Choose the Modernization Approach Before the Vendor
Global systems integrators are well suited to large, interconnected application portfolios. Modernization platforms provide automation and technical visibility. Specialist engineering partners are often a better fit for focused modernization projects where direct engineering involvement and incremental delivery matter most.
So before creating your shortlist, establish what needs to change, what must continue working, and how much operational risk your business can tolerate. Start with the modernization approach. Then choose the partner with evidence that it can deliver that approach for systems like yours.
CTA: Planning to modernize a legacy application? Plan incremental modernization now
Sources
- U.S. Government Accountability Office, Information Technology: Agencies Need to Continue Addressing Critical Legacy Systems (GAO-23-106821). https://www.gao.gov/products/gao-23-106821
- AWS Prescriptive Guidance, About the migration strategies (the 7 Rs). https://docs.aws.amazon.com/prescriptive-guidance/latest/large-migration-guide/migration-strategies.html
- Martin Fowler, Strangler Fig (updated 2024). https://martinfowler.com/bliki/StranglerFigApplication.html
- AWS Partner Solutions Finder. https://partners.amazonaws.com/
- Google Cloud Partner Finder. https://cloud.google.com/find-a-partner
- Microsoft partner directory. https://appsource.microsoft.com/en-us/marketplace/partner-dir
- Accenture, Application Modernization. https://www.accenture.com/us-en/services/cloud/application-transformation/application-modernization
- IBM, watsonx Code Assistant for Z. https://www.ibm.com/products/watsonx-code-assistant-z
- Kyndryl, Application Services. https://www.kyndryl.com/us/en/services/applications
- CAST, CAST Highlight. https://www.castsoftware.com/highlight
- CAST, CAST Imaging. https://www.castsoftware.com/imaging
- AWS, AWS Transform for mainframe. https://aws.amazon.com/transform/mainframe/
- AWS Documentation, Modernization of mainframe applications – AWS Transform. https://docs.aws.amazon.com/transform/latest/userguide/transform-app-mainframe.html
- Mechanical Orchard, Mainframe modernization, done right. https://www.mechanical-orchard.com/
- SoftServe, SoftServe Application Modernization Platform (SAMP) (PDF). https://www.softserveinc.com/files/pdf/softserve-application-modernization-platform-samp.pdf
- Endava, Core Modernisation (Dava.X). https://www.endava.com/dava-x/dava-x-core-modernisation
- Devox Software, AI-Assisted Legacy Modernization. https://devoxsoftware.com/legacy-modernization/ai-solution-accelerator/ai-assisted-legacy-modernization/
Frequently Asked Questions
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How do we modernize legacy applications without disrupting operations?
Start by identifying business-critical workflows, dependencies, integrations, and data consistency requirements. Establish baseline performance and functional tests before modifying production components.
Where feasible, use incremental modernization to replace individual modules while the existing application continues operating. Feature flags, staged releases, parallel testing, data reconciliation, and rollback procedures can reduce cutover risk.
Complete zero-downtime modernization is not always technically possible. The delivery team should define acceptable disruption limits, recovery targets, and clear go/no-go criteria before implementing each change.
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Should we rewrite or refactor our legacy application?
Refactoring is usually worth considering when the existing application still provides valuable business functionality and its main problems involve maintainability, outdated dependencies, or tightly coupled components.
A rewrite may be justified when the architecture fundamentally prevents required changes, the technology is no longer supportable, or the long-term cost of retaining the system exceeds replacement costs.
The decision should follow a technical and business assessment. In many cases, selective rebuilding combined with incremental refactoring offers a better balance between risk, investment, and delivery speed.
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What is application modernization, and how is it different from migration?
Application modernization is the process of improving existing software to make it more maintainable, secure, scalable, and suitable for current business requirements. It may involve updating frameworks, refactoring code, changing architecture, replacing components, or rebuilding applications.
Application migration primarily concerns moving software, data, or workloads to a different environment, such as the cloud. Migration can be part of modernization, but simply moving an unchanged application to new infrastructure does not necessarily resolve its architectural limitations.
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How long does a legacy application modernization project take?
The timeline depends on the system’s complexity, documentation, integrations, and required architectural changes. A focused framework upgrade or infrastructure migration may take several weeks or months, while rearchitecting a large business-critical application can require multiple delivery phases over a year or longer.
Discovery should establish a realistic schedule. For complex systems, a pilot can validate assumptions before the team commits to a broader timeline. Incremental modernization also allows useful improvements to reach production before the entire program is complete.
