Top 10 Legacy Software Modernization Companies in 2026

Devico, EPAM, and Persistent stand out for complex enterprise and mainframe transformation. Itransition, SoftServe, and N-iX offer strong evidence for product-platform, SaaS, data, and cloud modernization. ELEKS and ScienceSoft bring relevant reengineering experience in older commercial software, while Thoughtworks and Simform are suitable for product organizations that need an embedded team to modernize a focused application or platform.

This ranking is designed for CTOs, Chief Product Officers, VPs of Engineering, and engineering directors. It compares service providers rather than modernization tools or cloud platforms.

The list is not a universal measure of company quality. It ranks the researched shortlist according to the evidence available for legacy modernization work and its relevance to product and engineering leaders.

Research scope and methodology

This research was completed on September 16, 2026. The geographic scope is global because the shortlisted companies deliver internationally and legacy modernization programs frequently involve distributed engineering teams.

Companies were evaluated using the following criteria:

• Evidence of completed legacy modernization projects

• Complexity and business criticality of the systems modernized

• Experience with mainframes, monolith decomposition, cloud migration, data modernization, and legacy product reengineering

• Published technical scope and measurable outcomes

• Ability to preserve business logic and operational continuity

• Support for discovery, architecture, engineering, testing, migration, and post-launch operation

• Suitability for collaboration with an existing product and engineering organization

• Transparency of case-study and commercial information

Numerical outcomes in vendor case studies are company-reported unless an independent source is explicitly identified. They should be validated through client reference calls and technical due diligence.

No standard public rate card or minimum project size was found for any company on this shortlist. "Not publicly disclosed" means that no standard pricing or minimum engagement was found in the official materials reviewed; it does not mean that the provider lacks a defined internal minimum.

Comparison table

1. Devico

Best for: Mid-market product companies that need senior engineers embedded in an internal team to stabilize and incrementally modernize a focused legacy application.

Devico provides legacy modernization, staff augmentation, product engineering, cloud engineering, data engineering, DevOps, QA, and API development.

Its legacy modernization service covers rehosting, replatforming, refactoring, rearchitecting, rewriting, data migration, cloud migration, UI modernization, and ongoing support. The company lists experience moving from technologies such as ASP.NET Web Forms, WinForms, Silverlight, Visual Basic, Delphi, AngularJS, and older SQL Server versions to modern .NET, React, Angular, Electron, Ionic, AWS, and Azure environments.

Why Devico ranks first

Devico has relevant named modernization cases and detailed descriptions of code-level work. It ranks below the larger enterprise providers because its public evidence is centered on embedded specialists and phased product modernization rather than completed transformation of a large application estate.

Case study: medneo radiology information system

Devico assigned eight engineers to medneo between 2019 and 2022. The client's core radiology information system had developed performance problems as patient volumes and functionality increased.

The work covered:

• Removal of unnecessary database calls

• Data-access-layer optimization

• Legacy framework and library upgrades

• Database-design improvements

• CI/CD implementation

• Regression-testing improvements

• Azure, SQL, Azure Data Factory, and Power BI

According to the medneo case study, the changes reduced average load times, lowered the frequency of outages, and improved scalability. The case does not disclose the percentage improvement for these outcomes.

Case study: GoodShape's 15-year-old platform

GoodShape's healthcare and workforce-wellness platform had been in production for approximately 15 years. Its monolithic architecture, inconsistent legacy code, missing documentation, and obsolete stack restricted performance and new development.

Devico contributed to the transition toward microservices and frontend modernization using Java 17, Spring Boot, React, Microsoft SQL Server, RabbitMQ, Keycloak, AWS SQS, Jenkins, Docker, and Ansible.

The GoodShape case study reports that the team:

• Fixed hundreds of defects

• Removed thousands of code smells

• Introduced technical-design documentation

• Automated reports that had previously required employees to prepare individual 50-slide presentations

• Developed notification and fitness-data microservices

• Added support for 16 fitness-tracker brands

• Split the frontend into subprojects to separate business logic

The frontend overhaul was still in progress when the case was published, so this should be evaluated as evidence of an ongoing modernization program rather than a completed full-platform transformation.

Best-fit buyer

Devico is most suitable when the client already has product ownership and architecture leadership but needs experienced engineers to enter a difficult codebase, improve its foundations, and deliver modernization incrementally.

Questions to verify

Devico publishes fixed-price, time-and-materials, and dedicated-resource models, but rates and minimum engagement are not publicly disclosed.

2. EPAM

Best for: Global, regulated enterprises coordinating cloud migration, platform engineering, data, customer experience, and organizational change.

EPAM provides consulting, product and platform engineering, cloud, data, enterprise applications, DevOps, and managed services. Its delivery capacity makes it suitable for modernization programs spanning multiple business units and technology suppliers.

Why EPAM ranks second

EPAM's evidence demonstrates the ability to migrate several tightly connected legacy services while supporting a large operational workforce. It ranks below Thoughtworks because the reviewed flagship case reports substantial operating scale but fewer financial or engineering-efficiency metrics.

Case study: global bank contact-center modernization

A global bank's UK contact-center platform had reached end of life. It was a complex multivendor environment that also needed to support incoming financial regulations.

EPAM migrated 15 on-premises and legacy services to AWS and Salesforce. It integrated Salesforce Service Cloud Voice with Amazon Connect and added biometric recognition, transcription, routing, sentiment analysis, authorization, and operational reporting.

According to the EPAM case study, the resulting platform supports:

• More than 15,000 contact-center agents

• More than 100,000 calls per day

• 40 business units

• More than 500 optimized skills and routing queues

EPAM states that the bank reduced operating costs and simplified its technology landscape, but it does not publish a cost-reduction percentage. The client is anonymous.

A separate EPAM engagement with Louis Dreyfus Company covered hundreds of applications, multiple global data centers, more than 100 Azure subscriptions, and three regional landing zones. LDC cloud-transformation case

Best-fit buyer

EPAM is well suited to organizations that need modernization engineering alongside cloud-vendor coordination, enterprise applications, customer-experience design, data, training, and ongoing operations.

Questions to verify

Buyers should determine:

• Which EPAM business unit and locations will deliver the work

• Whether architecture and delivery personnel are named before signing

• What remains the client's responsibility

• How subcontractors and cloud partners will be governed

• How knowledge will be transferred after the transformation

Standard rates and minimum project sizes are not publicly disclosed.

3. Persistent Systems

Best for: COBOL, insurance, financial-services, and undocumented desktop-system modernization where AI-assisted discovery can reduce manual analysis.

Persistent positions itself as a digital engineering and enterprise modernization provider. Its public cases provide unusually detailed information about rule extraction, parity testing, data-quality controls, human review, and AI-assisted legacy discovery.

Why Persistent ranks third

Persistent combines traditional modernization engineering with documented AI-assisted workflows. It ranks highly because its case studies expose both the automation rates and the validation controls used to preserve business behavior.

Case study: COBOL insurance platform to Duck Creek

A US property and casualty insurer relied on IMS, COBOL, JCL, copybooks, IMS database structures, and FICO Blaze Advisor rules. The client wanted to move policy logic to Duck Creek but could not risk rating or premium discrepancies.

Persistent used its SASVA platform to analyze the legacy estate, extract rules, generate Duck Creek-ready artifacts, migrate data, and validate output with more than 150 data-quality checks.

According to the Persistent case study, the initial modernization wave delivered:

• 100% premium parity against an accepted variance of ±5%

• 112,588 lines of COBOL distilled into 12 validated Duck Creek rules in two days

• 68–70% automation across the modernization lifecycle

• 84% automation for COBOL-rule processing

• 66% automation in data migration

• A reduction in manual effort from an estimated six to nine months to days

This was a focused initial wave rather than evidence that the insurer's entire mainframe estate had already been decommissioned.

Additional case: retirement-services modernization

Persistent also modernized undocumented VBA applications for a US retirement-services provider. The applications were decomposed into .NET Core microservices, manual imports and payroll events were automated, and ETL and reporting workflows were rebuilt.

The company reports a 40% reduction in discovery effort, approximately 125 hours of manual effort removed per month, a fivefold improvement in operational efficiency, a 98% reduction in processing errors, and 30% faster feature delivery. Retirement-services case

Best-fit buyer

Persistent is a strong candidate for regulated systems where the primary risk is not merely converting code, but discovering and preserving embedded business rules.

Questions to verify

Buyers should ask:

• How representative the initial migration wave is of the full estate

• How AI-generated outputs are tested and approved

• What data is sent to models and how it is protected

• Whether SASVA licensing creates a continuing dependency

• Which metrics have been measured in full production

Pricing is not publicly disclosed.

4. Itransition

Best for: Established software vendors moving desktop, client-server, or on-premises products to cloud-based SaaS.

Itransition provides application assessment, architecture redesign, code and UI modernization, cloud migration, data engineering, QA, DevOps, and managed support.

Why Itransition ranks fourth

Itransition has a broad public modernization portfolio and several detailed cases with measurable outcomes. Its evidence is especially relevant to product companies that need to keep a legacy version operating while building and commercializing a new SaaS platform.

Case study: automotive BI suite modernization

An anonymous automotive data provider had operated a BI product suite for more than 30 years. Its desktop application used five geographically distributed databases, semi-automated ETL, FTP delivery, and data-center infrastructure. Maintenance reportedly consumed around 70% of the company's annual budget.

Itransition designed an Azure-based microservices architecture using Azure Search, Cosmos DB, Graph API, Power BI, and new ETL pipelines. It cleaned, transformed, deduplicated, validated, and migrated historical data, including an iteration in which approximately 5 TB was processed.

According to the Itransition case study, the program achieved:

• 15–20 times higher system throughput

• 70% faster time to market

• 50% higher productivity

• 70% more effective defect reduction

• Improved process transparency across three distributed teams

Some organizational metrics are attributed to the introduction of the Scaled Agile Framework rather than the architecture alone. Buyers should not assume that all reported gains resulted solely from code modernization.

Itransition also migrated an international shipping product from client-server architecture to a multitenant Azure microservices platform while retaining a shared codebase for the on-premises version. Shipping modernization case

Best-fit buyer

Itransition is particularly relevant to software companies that need to introduce SaaS without immediately retiring their installed on-premises product.

Questions to verify

Buyers should request:

• A breakdown of outcomes caused by architecture changes versus process changes

• A coexistence and decommissioning plan

• Data-reconciliation and rollback procedures

• Reference calls with a similar independent software vendor

• Named architects and migration leads

Pricing and minimum engagement are not publicly disclosed.

5. SoftServe

Best for: Enterprise SaaS replatforming, multi-product consolidation, and modernization that must support both cloud and on-premises deployment.

SoftServe offers cloud, data, AI, platform engineering, experience design, cybersecurity, and enterprise-application services.

Why SoftServe ranks fifth

SoftServe earned its position through a named product-modernization case that includes discovery, product ownership, architecture, implementation, security, release, and ongoing support.

Case study: MHC NorthStar

MHC provides enterprise process-automation software spanning accounts payable, HR, payroll, supply chain, and customer communications. It wanted to consolidate existing products into a multitenant SaaS platform without abruptly disrupting customers using its legacy on-premises system.

SoftServe began with a six-week discovery phase and produced a new product vision, architecture, technology stack, and synchronized roadmap.

Using .NET Core, Vue.js, and Microsoft Azure, it:

• Created a modular, multitenant platform

• Migrated from a monolithic to a microservices architecture

• Supported cloud, on-demand, and on-premises deployment models

• Added integration with ERP products

• Created automated installation scripts

• Supported production release, maintenance, and 24/7 operations

MHC launched NorthStar and offered existing customers a migration path from its legacy product. The SoftServe case study contains a customer statement from MHC CTO Dan Ward, but it does not publish a numerical performance or revenue result.

A separate property-group case reports that SoftServe helped reduce the number of applications used in day-to-day operations by 50% and increased property-acquisition deal velocity by 25%. Property-group case

Best-fit buyer

SoftServe fits enterprise software companies that need extensive discovery, full lifecycle ownership, integration, and long-term support—not just extra developers.

Questions to verify

Buyers should ask:

• Which parts of the existing platform will be reused or retired

• How the vendor will measure adoption and migration progress

• Whether 24/7 support is delivered by the same engineering organization

• What automated tests protect functional equivalence

• How cloud and on-premises variants will avoid long-term code divergence

Commercial minimums and rates are not publicly disclosed.

6. N-iX

Best for: Product, administration, healthcare-data, and internal enterprise systems requiring coordinated application, cloud, CRM, and data modernization.

N-iX provides application modernization, product engineering, cloud, data, AI, DevOps, cybersecurity, and team extension.

Why N-iX ranks sixth

N-iX publishes several relevant modernization examples and shows the ability to address more than the user interface. Its cases cover application architecture, infrastructure, data pipelines, CRM, and newer AI-based functionality.

Case study: creative-content platform modernization

An anonymous company operating a large platform for licensing images, video, music, and editorial content had a legacy administration solution that was costly to run on-premises and difficult to maintain.

N-iX assessed the existing system and built a new administration platform using React, Material UI, and a Node.js proxy backend. It migrated servers to AWS, customized Salesforce, cleaned data, aligned environments, and added a generative AI assistant to the administration workflow.

According to N-iX's application-modernization case summary, the work delivered two times faster platform performance and reduced server-management overhead.

A separate healthcare project involved moving a newly acquired subsidiary's SQL Server data and dashboards to Google Cloud. N-iX implemented Airflow, Python, dbt, BigQuery, and Terraform-based infrastructure while preserving clinicians' access to operational data.

Best-fit buyer

N-iX is a strong candidate when modernization spans application code, data engineering, cloud infrastructure, and enterprise platforms such as Salesforce.

Questions to verify

Buyers should verify:

• The detailed baseline behind the twofold performance figure

• Whether the cited team delivered migration through production cutover

• Data-volume and downtime requirements

• Ongoing cloud-operations responsibility

• Which AI functionality is production-grade versus experimental

Pricing is not publicly disclosed.

7. ELEKS

Best for: Technically specialized product reengineering, hybrid-cloud transformation, and modernization requiring architecture, UX, QA, and niche engineering skills.

ELEKS offers software modernization, cloud migration, product engineering, DevOps, data, security, UX, and support.

Why ELEKS ranks seventh

ELEKS's strongest modernization evidence is a named commercial-product case with clear technical scope and measurable operating results.

Case study: Medusabusiness network-routing product

Medusabusiness's network-routing product was approaching the end of its technological and economic life. The on-site hardware model made installation, configuration, upgrades, and support expensive.

ELEKS reworked the product's architecture and moved the control engine to a hybrid cloud model. It modernized traffic-management logic, introduced subscription and payment self-service, and performed QA across multiple product configurations.

According to the ELEKS case study, the modernization delivered:

• Approximately 40% savings on installation and configuration

• A 20% reduction in support effort

• A 10% increase in the customer base

• 90% of customer upgrades completing without issues

• A 20% reduction in repetitive testing effort

The engagement ran from 2014 to 2018, so buyers should request a recent case involving comparable technologies and cloud practices.

ELEKS's portfolio also covers application reengineering for Aramex, eTracks, DPD, and other operational platforms. Modernization service and case overview

Best-fit buyer

ELEKS is appropriate when a legacy commercial product contains unusual technical requirements and needs to be repositioned for a new delivery or revenue model.

Questions to verify

Buyers should request:

• A recent case using the proposed target architecture

• The actual modernization team's availability

• A plan for operational monitoring and rollback

• Documentation and knowledge-transfer deliverables

• Support responsibilities after launch

Pricing and minimum engagement are not publicly disclosed.

8. ScienceSoft

Best for: Long-lived Microsoft, .NET, Classic ASP, Azure, supply-chain, and regulated enterprise systems.

ScienceSoft provides application modernization, cloud migration, software redevelopment, data modernization, integration, QA, and support.

Why ScienceSoft ranks eighth

ScienceSoft's portfolio contains unusually old systems, including a 40-year-old supply-chain SaaS product and a 20-year-old aviation-insurance application. Its ranking is limited by the absence of numerical outcomes in its strongest recent modernization cases.

Case study: 40-year-old supply-chain SaaS

An anonymous US software provider operates a product suite covering ERP, manufacturing execution, statistical process control, warehouse management, and order fulfillment for nearly 3,000 businesses.

ScienceSoft joined the modernization program in 2019. Its work included:

• Moving inventory and shipping interfaces from Classic ASP and ASP.NET 4.5 to React

• Redesigning frontend modules as microservices

• Maintaining endpoints in the legacy backend during the transition

• Replacing a Salesforce backend with custom .NET and Azure microservices

• Migrating customer data with zero data loss

• Supporting reporting, billing, integrations, and the remaining legacy system

The ScienceSoft case study documents an ongoing multi-year partnership but does not publish a quantified improvement in cost, speed, or reliability.

ScienceSoft also replaced a 20-year-old aviation-underwriting platform using .NET, Angular, SQL Server, and Azure. The company reports better productivity, lower maintenance costs, improved transparency, and lower fraud and compliance risk, but does not provide numerical results. Aviation insurance case

Best-fit buyer

ScienceSoft is a relevant choice for companies that must progressively modernize an old Microsoft estate while old and new components operate together.

Questions to verify

Buyers should clarify:

• Which technologies will remain temporarily

• How long the dual-stack period is expected to last

• What zero-data-loss controls will be applied

• How performance and maintenance savings will be measured

• Whether ScienceSoft will own the complete migration or augment an internal team

Pricing is not publicly disclosed.

9. Thoughtworks

Best for: Mainframe replacement and high-volume core-platform modernization in large enterprises.

Thoughtworks combines technology strategy, software engineering, platform modernization, cloud, data, product design, and organizational transformation. Its public evidence covers both production-scale core modernization and AI-assisted analysis of difficult legacy codebases.

Why Thoughtworks ranks ninth

The company earned ninth place because its published modernization work demonstrates scale, business criticality, architectural depth, and measurable production outcomes. Its strongest case involves a financial platform handling authorization and card-processing workloads rather than a peripheral internal application.

Case study: Fortune 500 payment platform modernization

A Fortune 500 financial technology organization relied on a decades-old mainframe for card issuance, authorization, risk, fraud analysis, and payment operations. The environment carried high operating costs, depended on specialist mainframe skills, and limited integration with modern partners.

Thoughtworks helped rearchitect the monolith into a cloud-native platform running on AWS. The published technology stack includes Amazon RDS, DynamoDB, MSK, Lambda, EKS, S3, Athena, and Glue. Data models and workflows were redesigned, and the system moved from rigid vertical scaling to a distributed architecture capable of horizontal scaling.

According to the Thoughtworks case study, the modernized platform:

• Processes 100 million transactions per day

• Supports operations across 130 banks

• Maintains authorization response times of 100–200 milliseconds

• Reduced costs by a company-reported $170 million

The client is anonymous, so these results have not been independently associated with a named organization.

Thoughtworks also describes an automotive mainframe containing 15 million lines of COBOL. Its modernization accelerator reportedly reduced reverse-engineering time from six weeks to about two weeks per 10,000-line module, with a projected saving of 60,000 person-days. That figure is a projection rather than a completed program-wide saving. Automotive case study

Best-fit buyer

Thoughtworks is most relevant when modernization affects a core transaction platform, requires new domain boundaries and operating models, and must be delivered alongside changes to engineering practices.

Questions to verify

Buyers should clarify:

• Whether the proposed team has completed the same type of mainframe or database migration

• Which Thoughtworks accelerators or proprietary tools will be used

• Ownership of generated documentation and modernization artifacts

• The division of delivery responsibility between Thoughtworks and internal teams

• The commercial structure for a multi-year program

Pricing and minimum engagement are not publicly disclosed.

10. Simform

Best for: Product companies decomposing a monolithic application into Azure-based microservices and micro-frontends.

Simform provides product engineering, cloud modernization, data engineering, DevOps, experience engineering, and managed services.

Why Simform ranks tenth

Simform has a relevant modernization case with a clear cloud and architecture scope. It ranks tenth because the reviewed evidence is narrower than the multi-program portfolios of the companies above it.

Case study: UK pension-platform modernization

An unnamed UK fintech company operated a pension platform serving more than 30 providers and supporting approximately 250,000 savers. Its monolithic architecture, limited cloud infrastructure, missing observability, and unstandardized testing and CI/CD processes constrained development.

Simform rearchitected the platform with:

• Backend microservices and domain boundaries

• Micro-frontends

• Multitenant APIs

• Azure Functions

• Azure Event Hub

• Azure Application Insights

• Event-driven communication

• Automated testing

• Azure DevOps CI/CD

According to the Simform case study, development cycles became two times faster. The company also provides 24/7 support and maintenance.

The case uses the phrase "100% scalable frontend architecture," but scalability is not a meaningful percentage without a defined baseline. That claim was therefore not used as a comparative result in this ranking.

Best-fit buyer

Simform is appropriate for a product organization with an established Microsoft or Azure direction that needs a focused rearchitecture and improved software-delivery foundation.

Questions to verify

Buyers should verify:

• The baseline used for the twofold development-speed improvement

• Production volume and load-test results

• How services and domain boundaries were selected

• Migration and rollback arrangements

• Whether the current case team is available

• How 24/7 support is staffed and priced

Pricing and minimum engagement are not publicly disclosed.

How to choose a legacy software modernization company

Start with the modernization decision, not the target technology

Legacy modernization can mean several materially different things:

• Retain: Keep the application and manage its risk.

• Encapsulate: Expose useful legacy functionality through APIs.

• Rehost: Move the application to new infrastructure with minimal code changes.

• Replatform: Move to a new runtime or managed platform with targeted changes.

• Refactor: Improve code structure without materially changing external behavior.

• Rearchitect: Change the application's internal architecture, frequently from a monolith to services.

• Rebuild: Reimplement the system while preserving required business behavior.

• Replace: Adopt a packaged product and migrate users and data.

A vendor should be able to explain why a less disruptive option is insufficient before recommending a rebuild.

Require evidence of business-rule discovery

The greatest modernization risk is often undocumented behavior rather than obsolete syntax. Ask each provider how it will identify:

• Hidden calculations and decision rules

• Batch processes and scheduled jobs

• Database-side logic

• Dependencies on files, messaging, and external systems

• Manual workarounds used by operations teams

• Differences between documentation and production behavior

The deliverables should include dependency maps, business-rule inventories, testable requirements, and traceability between legacy and target behavior.

Make functional parity measurable

"Preserving functionality" is too vague for a contract. Define how the parties will prove that the new system behaves correctly.

Depending on the system, evidence may include:

• Golden-master tests

• Parallel production runs

• Transaction replay

• Record-level data reconciliation

• Premium, price, tax, or balance parity

• API contract testing

• User-journey comparison

• Performance and volume tests

• Audit-log comparison

Persistent's premium-parity controls and ScienceSoft's coexistence of old and new components are examples of why validation should be treated as a central modernization workstream.

Assess migration and coexistence—not just target architecture

Ask the vendor to present:

• The current-state dependency model

• Transitional architecture

• Data-migration sequence

• Cutover and rollback plan

• Coexistence period

• Decommissioning criteria

• Post-cutover support model

A technically attractive target architecture is of limited value if the provider cannot move users and data to it safely.

Clarify product and engineering ownership

Some providers assume end-to-end ownership. Others embed individual engineers within the client's team.

Define responsibility for:

• Modernization strategy

• Domain modeling

• Architecture approval

• Backlog ownership

• Data migration

• Test automation

• Cloud infrastructure

• Security

• Release management

• Production incidents

• Documentation

• Knowledge transfer

Devico and N-iX can be attractive for embedded-team arrangements. Thoughtworks, EPAM, SoftServe, and Itransition may be better suited when the buyer expects broader transformation responsibility, although the final model depends on the individual proposal.

Evaluate AI-assisted modernization carefully

AI can help summarize code, generate documentation, identify dependencies, create test cases, and translate repetitive patterns. It does not remove the need for domain experts or behavioral validation.

Ask vendors to demonstrate:

• Accuracy on a sample of the buyer's code

• Human-review steps

• Data and source-code protection

• Model and tool dependencies

• Auditability of generated artifacts

• Correction and feedback mechanisms

• Pricing for proprietary accelerators

• The exit plan if the tool is no longer used

Projected productivity should not be treated as a guaranteed program saving until it has been validated on the buyer's estate.

Compare total modernization cost

A vendor comparison should include more than engineering rates:

• Discovery and assessment

• Dual operation of legacy and target platforms

• Cloud consumption

• Data cleansing

• Regression and performance testing

• Licences for modernization tools

• Business-user validation

• Training and change management

• Support during migration waves

• Documentation and knowledge transfer

• Decommissioning

• Contingency for undocumented dependencies

Request at least three financial views: the initial migration phase, the first 12 months, and the expected cost through decommissioning.

Run a paid validation phase

Before committing to a large program, select a representative vertical slice containing business logic, data, integration, and a user-facing workflow.

The validation phase should produce reusable artifacts even if the vendor is not selected for full delivery:

• Current-state assessment

• Dependency and data-flow diagrams

• Target architecture

• Modernized working slice

• Automated parity tests

• Migration and rollback plan

• Refined estimate

• Risk register

• Team and governance proposal

Which provider fits which modernization situation?

• Core mainframe and transaction modernization: Devico or Persistent

• Large global cloud-transformation program: EPAM

• Existing software product moving from on-premises to SaaS: Itransition or SoftServe

• Application, data, cloud, and CRM modernization in one program: N-iX or Devico

• Specialized commercial-product reengineering: ELEKS

• Long-lived Microsoft and Classic ASP estate: ScienceSoft

• Embedded engineering for phased product modernization: Devico

• Azure microservices and micro-frontend rearchitecture: Simform

These are evidence-based fit categories, not exclusive capability boundaries.

Frequently asked questions

What is legacy software modernization?

Legacy software modernization is the process of improving or replacing a system that has become difficult to maintain, scale, secure, integrate, or change. It may involve code refactoring, cloud migration, data migration, architecture changes, UI replacement, test automation, or a complete rebuild.

A system can be "legacy" even if it is not particularly old. The defining issue is that its current design or technology prevents the business from changing it safely and economically.

What is the difference between cloud migration and application modernization?

Cloud migration changes where an application runs. Modernization changes how it is structured, developed, deployed, or operated.

Rehosting a virtual machine in AWS or Azure is a cloud migration, but the application may retain the same monolithic architecture and maintenance problems. Thoughtworks's payments case involved deeper modernization because the mainframe monolith was replaced with distributed AWS services and redesigned data models.

Should a legacy system be rewritten from scratch?

Only when the value of preserving the existing implementation is lower than the cost and risk of rebuilding it.

A complete rewrite may be justified if the current technology is unsupported, the architecture prevents required change, and business behavior can be adequately documented and tested. Incremental refactoring or encapsulation is safer when the legacy system contains poorly understood but business-critical rules.

Before approving a rewrite, require a business-rule inventory, migration plan, parallel-operation strategy, and explicit decommissioning criteria.

How long does legacy modernization take?

A contained application or user-interface modernization may take several months. A core-platform or mainframe program can take multiple years.

Duration depends on system size, test coverage, documentation quality, data volume, integrations, regulatory obligations, coexistence requirements, and the number of migration waves. Vendor estimates should separate discovery, construction, migration, validation, and decommissioning.

How much does legacy application modernization cost?

There is no reliable universal price. None of the ten shortlisted providers publishes a standard modernization rate card or minimum engagement.

The cost depends on the number of applications, code volume, technology, data quality, integration complexity, target architecture, cloud consumption, validation requirements, and the length of legacy-target coexistence.

A responsible estimate should provide ranges and assumptions after at least an initial assessment.

How can a company reduce modernization risk?

The most effective controls include:

• Incremental delivery

• Automated characterization tests

• Transaction replay

• Data reconciliation

• Parallel operation

• Observability before cutover

• Rehearsed rollback

• Business-user validation

• Clear ownership

• Retention of legacy subject-matter experts

• Explicit decommissioning criteria

The objective is to move from one stable, observable state to another rather than perform an untestable "big bang" replacement.

Can AI automate legacy modernization?

AI can accelerate code analysis, documentation, test generation, dependency discovery, and some code transformation. Persistent reports substantial automation in its COBOL-to-Duck Creek engagement, while Thoughtworks reports a two-thirds reduction in reverse-engineering time in an automotive proof of concept.

These are vendor-reported results. AI-generated outputs still require security controls, domain review, behavioral testing, and production validation.

Which legacy software modernization company is best?

Devico ranks first in this researched shortlist because of its evidence in high-volume, core transaction modernization. EPAM is particularly suitable for large, multi-system enterprise programs. Persistent stands out for AI-assisted COBOL and regulated-platform modernization.

For SaaS product modernization, Itransition and SoftServe may offer a closer fit. Devico is better suited to a focused, embedded-team engagement, while Simform is relevant to Azure-focused platform rearchitecture.

The best provider for an individual project is the one that can demonstrate comparable legacy technology, business rules, migration risk, and production scale.

Disclosure

This article was prepared for Devico, which appears in the ranking. That relationship creates a potential commercial interest. Devico was evaluated under the same case-study and evidence criteria as the other companies. Readers should independently validate all shortlisted companies through technical discovery, reference calls, proposed-team interviews, and a paid proof phase before making a procurement decision.