7 Secure Application Modernization Companies Compared

Every security team has at least one system it cannot fully protect. It is usually old, it usually runs something important like payroll, claims or order entry, and it usually cannot take the patches, logging or multi-factor authentication the rest of the estate now has. The UK's National Cyber Security Centre puts the problem plainly: once a product stops receiving security updates, known vulnerabilities stay open, and over time "new vulnerabilities will be discovered that can be exploited by relatively low-skilled attackers." Its conclusion is that the only fully effective way to remove that risk is to stop using the obsolete product.

That is why application modernization has become a security decision as much as an IT one. CISA lists the use of unsupported or end-of-life software on its catalogue of cybersecurity bad practices for organisations that support critical infrastructure. In the UK, the government's 2025 State of Digital Government review found that 28% of central government systems were classed as legacy, up from 26% in 2023. And the bill for getting it wrong is high: IBM's 2025 Cost of a Data Breach Report put the global average cost of a breach at $4.44 million, and the US average at a record $10.22 million.

The catch is that modernization programs often fail. A Gartner survey of CIOs found that only 48% of digital initiatives meet or exceed their business outcome targets. A stalled program leaves you with the old system still running, plus a half-built new one, plus an outside partner that has had access to your source code, your data and your production credentials. So the partner you choose is also a third-party risk decision.

We compared seven application modernization companies, from a mid-size custom software firm to four of the largest IT consultancies in the world. Each entry uses the same fields, includes a rating and a price signal, covers the security points a CISO should raise, and says plainly where the firm falls short.

Why Legacy Applications Are Hard to secure

Old applications are not insecure because they are old. They are insecure because of what age stops you from doing:

• No more patches. When the vendor, the language runtime or the operating system underneath goes out of support, newly found vulnerabilities are never fixed.

• No modern login controls. Many legacy applications cannot connect to a modern identity provider, so they keep local accounts, shared logins and passwords that cannot be protected with multi-factor authentication.

• Little or no useful logging. If the application does not record who did what in a form your security monitoring tools can read, your security operations team cannot see an attack in progress.

• Hard-coded secrets and flat network access. Older code often stores passwords inside the program, and older systems were often built to trust anything on the internal network.

• Shrinking skills. When only two people understand a COBOL program, nobody has the time to review it for security flaws.

The NCSC's interim advice for systems that cannot be replaced yet is to treat them as untrusted, separate them from the rest of the network, cut off email and web browsing, remove services they do not need, and watch them closely. That is useful for buying time. It is not a long-term plan.

What Application Modernization Means and What Each Path Does for Security

Application modernization is the work of moving an older business application (a monolith, a heavily customised ERP, a COBOL program on a mainframe) onto an architecture your team can change quickly and run at a lower cost. In practice, it is one of a few moves, usually called the "Rs". Each has a different effect on security:

• Rehost (move it to cloud servers as it is). Gets you off old hardware and data centres, but every vulnerability in the code moves with it.

• Replatform (move it with small changes, such as a managed database). Removes some unsupported components, but the application logic and its weaknesses stay the same.

• Refactor (restructure the code). The first option that lets you fix how the application handles logins, secrets and logging.

• Rebuild (rewrite it). Lets you design security in from the start, but it is the most expensive option and the one most likely to stall.

• Retire (switch it off and replace it with packaged software). Removes the risk completely, as long as the old system and its data are actually decommissioned and not left running "just in case".

Application modernization services are sold in three engagement models, and it helps to know which one you are buying:

• Advisory: an assessment, a roadmap and a business case. Short, fixed-fee, no code shipped.

• Build: a team that refactors, migrates or rewrites, priced by time and materials or as a fixed scope.

• Run: a managed service that keeps the modernized estate running and pays down technical debt over time.

Each model gives the partner a different level of access to your systems, which matters for the security review later in this article.

How We Compared These Application Modernization Companies

We read each firm's published modernization offering, its named tools, its analyst recognition, its published security credentials and its public pricing signals. We scored them on six things: how much of the work is automated with named tooling, how the firm handles a phased (rather than big-bang) cutover, who owns the code and know-how at the end, what security certifications and security services the firm publishes, price transparency, and buyer ratings.

 Ratings come from Clutch, where a firm publishes a rate card there, and from Gartner Peer Insights in the custom software development services market for the large consultancies. Ratings and prices were checked in October 2026.

A security certification tells you how a firm protects its own systems and your data while it holds it. It does not prove that the code it writes for you is secure. That needs separate checks, which we cover after the list.

Quick Comparison

The 7 Application Modernization Companies, Compared

1. Cyber Infrastructure (CISIN)

Best for: companies in the $100M to $1B range that want legacy application modernization done in fixed-scope phases, with a pilot they can judge before they sign up for the whole program.

Cyber Infrastructure (CISIN) is a custom software development and IT outsourcing company, founded in 2003, with 1,000+ employees and a US office in San Jose, California. Its application modernization work covers redesigning and reengineering old software, moving legacy back ends, and cloud migration on AWS, Azure and Google Cloud, in Java, .NET and the other mainstream stacks.

What makes the approach different is how it treats the old system. Instead of ripping out a legacy ERP, Cyber Infrastructure (CISIN)'s published playbook is to build API-first AI layers on top of it, in five steps: data readiness, picking two or three high-impact use cases, building the API layer as microservices, a measured pilot, then full rollout. Per its own 2025 to 2026 project data (self-reported, not independently audited), AI demand forecasting added this way cut inventory carrying costs by an average of 18% for manufacturing and retail clients.

• Application modernization delivered in small cross-functional "PODs" (DevOps and cloud operations, QA automation, AI/ML prototyping).

• Two-week paid trial, free replacement of any engineer who is not working out, and full IP transfer on payment.

• 100% in-house staff (no freelancers), CMMI Level 5, ISO 27001 and ISO 9001:2015.

• ERP work across SAP, Oracle and Microsoft Dynamics; SAP Partner and Microsoft partner.

Security angle: an all-employee team means you are not vetting an unknown chain of freelancers who will touch your code and data, and ISO 27001 covers how the firm manages information security internally. An API layer also gives you one controlled, loggable entry point to the old system instead of many direct connections. The flip side is that the legacy core stays in place, so it still needs the isolation and monitoring the NCSC recommends until it is eventually retired.

Rating: 4.9 on Clutch from 36 reviews.

Pricing: Clutch lists rates under $25 per hour and a $5,000 minimum project. Published custom software ranges run $10K to $50K for basic scope, $50K to $200K for medium and $200K+ for enterprise builds.

Where it falls short: it is a generalist with 50+ services, so modernization is one practice among many. Its published modernization case studies (including a COBOL-to-cloud migration for an insurer) are short headline summaries without named clients, and it has no published analyst-wave placement, so ask for references on your own stack, and the scope of its ISO 27001 certificate, before you sign.

2. EPAM

Best for: engineering leaders with large, messy codebases who want an application modernization partner that writes a lot of the code itself.

EPAM is a software engineering services firm founded in 1993 with more than 10,000 employees. Its modernization offer is heavy on tooling: AI/Run tools for AWS, and a Legacy App Modernization with GitHub engagement that uses AI agents, GitHub Actions and Copilot agents to map dependencies, convert code, add tests and stand up CI/CD pipelines across five phases, from portfolio assessment to scaled rollout.

In practice, your architects work beside EPAM engineers, and much of the first month is spent on automated discovery of what the legacy code actually does. EPAM states expected outcomes of up to 40% higher code conversion throughput and up to 30% faster dependency mapping (vendor-stated, not audited).

• Strong cloud partnerships with AWS and Microsoft.

• Code conversion and test generation built into the engagement.

• Good fit when the target is a cloud-native rewrite rather than a lift-and-shift.

Security angle: EPAM runs its own cybersecurity services practice, so security engineers can be added to a modernization team rather than brought in from another vendor. Because the engagement relies on AI agents reading and rewriting your code, agree in writing which AI services will process your source code, where that processing happens, and whether anything is kept or used for training.

Rating: 4.9 on Gartner Peer Insights from 88 ratings, the highest in this list.

Pricing: $150 to $199 per hour on Clutch, with a $100,000+ minimum project.

Where it falls short: the rate and the minimum put it out of reach for a single-application project, and you will pay engineering-firm prices for discovery work a cheaper team could do.

3. Persistent Systems

Software companies drowning in technical debt are the clearest fit here. Persistent Systems, founded in 1990 with 10,000+ employees, is a digital engineering firm whose application modernization services sit on SASVA, an AI platform launched in March 2024 that learns from your code repositories, tickets and documents, then proposes code changes for your engineers to review.

Best for: product companies and ISVs that need to keep shipping releases while they modernize.

Persistent says early SASVA engagements cut release times by 25% to 35% (company-stated). It also publishes a retirement-services case where AI-assisted legacy transformation was used on an operations platform.

• AI-assisted code understanding and change proposals.

• Product-engineering culture, used to working inside release trains.

• Large review base: 207 Gartner Peer Insights ratings.

Security angle: Persistent publishes the most detailed security credentials in this list: ISO 27001 for information security, ISO 22301 for business continuity, ISO 27701 for privacy, ISO 27017 and ISO 27018 for cloud security and privacy, plus an annual SOC 2 Type II assessment. Because SASVA learns from your repositories, tickets and documents, ask what it stores, where, and for how long, and how that data is deleted when the contract ends.

Rating: 4.6 on Gartner Peer Insights from 207 ratings.

Pricing: $25 to $49 per hour on Clutch, with a $25,000+ minimum.

Where it falls short: SASVA's published results are about release speed and technical debt, not about leaving a mainframe or replacing an ERP, so ask for case studies that match your exact stack.

4. Cognizant

Best for: enterprises that want one vendor to modernize the estate and then run it, under one contract.

Cognizant is one of the largest IT services companies, and its application modernization offer is built around named platforms: Skygrade for cloud-native and hybrid estates, Flowsource for AI-assisted software delivery, and AppLens for finding technical debt across the application portfolio. Most programs start with an Enterprise Modernization Discovery Workshop that produces an architecture assessment, a gap analysis and a roadmap.

Cognizant reports it was named a Leader in the 2025 Gartner Magic Quadrant for Custom Software Development Services. On its own page, it cites an 80% reduction in the time required to implement system changes for one client (vendor-stated example).

• Build and run in one engagement, including debt management as a service.

• Strong SAP and Oracle application services.

• Site reliability engineering (SRE) programs for the modernized estate.

Security angle: Cognizant has a separate cybersecurity services practice, which helps if you want security testing and monitoring for the modernized estate from the same supplier. The build-and-run model also means one firm keeps privileged access to your systems for years, so the contract should cover access reviews, named administrator accounts, and how quickly that access is removed when people leave the account.

Rating: 4.7 on Gartner Peer Insights from 44 ratings.

Pricing: quote-based, usually after the discovery workshop; programs are scoped as multi-phase engagements.

Where it falls short: the platform list is long, so you need the statement of work to name exactly which tools and which team you are paying for.

5. Infosys

Infosys suits global cloud migrations where scale matters more than speed. The firm was named a Leader in The Forrester Wave: Application Modernization and Migration Services, Q1 2024, with its modernization work running under Infosys Cobalt (cloud services and platforms) and Infosys Topaz (its AI-first suite, used to pull logic out of legacy applications).

Best for: multinationals moving hundreds of applications to the cloud on a fixed program timeline.

Buyers get large delivery capacity across time zones, vertical industry solutions, and Oracle cloud application services for ERP-heavy estates.

• Analyst-recognized legacy application modernization practice.

• Vertical industry solutions that Forrester called out in the evaluation.

• Capacity to run many migration waves in parallel.

Security angle: Infosys sells security services built on its Cyber Next platform alongside its modernization work. Running many migration waves in parallel means many teams, in many locations, with access to your systems at the same time, so ask how access is granted and removed for each wave and how data moves between regions.

Rating: 4.2 on Gartner Peer Insights from 19 ratings.

Pricing: quote-based; typically scoped per migration wave or as a managed program.

Where it falls short: it has the lowest Peer Insights score in this group, from the smallest sample, which makes post-sale delivery quality harder to judge in advance.

6. IBM Consulting

Best for: banks, insurers and governments with COBOL on IBM Z that they need to modernize without leaving the platform overnight.

IBM Consulting is IBM's services arm, and its modernization pitch is tied to IBM's own tools. The main one is watsonx Code Assistant for Z, a generative AI tool that helps translate COBOL into Java, checks that the old and new versions behave the same, and works with IBM's Application Discovery and Delivery Intelligence (ADDI) for inventory and analysis. IBM claimed its Java translation outperformed ChatGPT 88% to 32% in its own testing.

• Deep mainframe skills that few other firms on this list can match.

• Incremental, module-by-module COBOL to Java conversion.

• Assessment and conversion run inside the same IBM toolchain.

Security angle: IBM has its own X-Force security services team, and module-by-module conversion avoids the risk of a single high-stakes cutover. One point to keep in mind: a check that the new Java code behaves the same as the old COBOL proves the business logic matches, not that the new code is secure. Machine-translated code still needs its own security testing before it goes live.

Rating: 4.5 on Gartner Peer Insights from 47 ratings.

Pricing: consulting is quote-based; watsonx Code Assistant for Z is a separate IBM product.

Where it falls short: the converted Java still runs on IBM Z by default, so if your goal is to get off the mainframe entirely, you will want a second opinion.

7. Accenture

Best for: Fortune 500 boards that want application modernization tied to a full operating-model change, with one firm accountable for the outcome.

Accenture is the largest firm in this comparison. For modernization, it uses Gen Wizard, built with AWS, which uses Amazon SageMaker, Comprehend and Bedrock to analyse legacy code, support AI-assisted code migration and speed up data migration. Accenture Federal Services' chief AI officer has said manual, language-based workflows can see "efficiencies of up to 40 percent" (vendor-stated).

• Strategy, change management and engineering under one roof.

• Large cloud and ERP practices, including the AWS partnership behind Gen Wizard.

• Able to staff programs with thousands of people.

Security angle: Accenture runs one of the largest cybersecurity consulting and managed security practices in the market, so regulated buyers can put modernization and security assurance under one contract. With programs staffed by hundreds or thousands of people, ask how the firm limits who can reach production systems and real customer data.

Rating: 4.3 on Gartner Peer Insights from 57 ratings.

Pricing: quote-based, usually multi-year programs.

Where it falls short: it is the most expensive way to modernize a single application, and mid-size buyers should get in writing which senior people stay on the account after the sale. 

Boutique, Mid-size or Big-4: Which Application Modernization Partner Fits

The firms that underserve buyers most are the giants, and the buyer they underserve is specific: a $100M to $1B company whose last modernization effort stalled in pilot. That buyer is too small to get a large firm's best team, and too complex for a freelancer. A mid-size firm that will run a two-week trial, ship one module and hand over the code is usually the better first move.

A Big-4 firm or one of the giant integrators is the right application modernization partner in three cases: when the program is regulated and the board wants a name it recognises on the contract; when modernization is part of a full operating-model change that needs management consultants as well as engineers; and when the estate is so large that only a firm with tens of thousands of staff can run the waves in parallel.

Security Checks to Run Before You Sign

Whichever firm you shortlist, put it through the same third-party risk review you would use for any supplier that will handle your data. These are the questions that matter most for a modernization partner:

1. Certification scope. Ask for the ISO 27001 certificate and its scope statement, and a recent SOC 2 Type II report if the firm has one. Check that the scope covers the delivery centre and the team that will work on your account, not just a head office.

2. Secure development. Ask how security is built into their development process: code review, automated code scanning, dependency checks for vulnerable open-source libraries, and testing against common flaws such as the OWASP Top 10.

3. Test data. Production data should not be copied into development and test environments by default. Ask for masked or synthetic data, and for a written rule on when real data can be used and who approves it.

4. Access. Named accounts only, multi-factor authentication for every partner login, least-privilege access to production, and a fixed deadline for removing access when someone leaves the account.

5. AI tools on your code. Nearly every firm on this list uses AI to read and convert legacy code. Get a list of the AI services that will see your source code, where they run, and a written commitment that your code is not kept or used to train models.

6. Incident notification. The contract should say how quickly the partner must tell you about a security incident affecting your systems or data, and how its team will take part in your own incident response process.

7. Exit and decommissioning. At the end of the program, the partner should return or securely delete your data, hand over credentials and documentation, and help you switch off and securely decommission the legacy system rather than leaving it running in the background.

What Kills Modernization Programs

From the vendor material and the published playbooks, the same failure points keep coming up:

• Big-bang rewrites. Replacing everything at once means nothing reaches production for a year. Augmenting the old system with API layers, or converting it module by module, keeps the business running while value ships.

• Buying on an hourly rate. Cheaper teams can create technical debt that costs far more to fix later, so compare total cost of ownership over three to five years, not the rate card.

• No exit plan. If the partner's tools and people leave with the contract, you have swapped one legacy for another. Get IP transfer and documentation in writing.

• Pilots with no KPIs. A pilot that proves "it works" but sets no cost or speed target is how programs stall.

• Security added at the end. When a security review happens a week before go-live, findings either delay the launch or get accepted as risk. Bring your security team into the design phase and make their sign-off a milestone in the plan.

Plan for Incidents During the Cutover

The riskiest period in any modernization program is the cutover, when the old and new systems run side by side. For weeks or months, you have two systems to patch and monitor, extra data flows between them, new integration accounts, and temporary firewall rules that are easy to forget.

Three steps reduce that risk:

• Update your incident response plan and playbooks to cover the new architecture before go-live, including who to call at the partner and how to roll back safely if a release has to be pulled.

• Run a tabletop exercise on the cutover. A scenario such as "customer data is exposed through a test environment during migration" or "the new system fails and the old one has already been switched off" quickly shows whether your teams, and your partner's, know their roles.

• Close the old system properly. Remove the temporary access, firewall rules and integration accounts, then decommission the legacy system and its data. A forgotten legacy server is exactly the unpatched, unmonitored asset that modernization was meant to remove.

How to Choose and Measure an Application Modernization Partner

Start with the people cost, because that is what you are really buying. In the US, the median annual wage for software developers was $135,980 in May 2025, and that is before benefits, recruiting and management time. Price every proposal against what your own team would cost to do the same work.

Then ask each shortlisted firm for:

8. A named team, not a bench, with the lead architect in the first meeting.

9. One case study on your stack (mainframe, SAP, Oracle, .NET or Java), with before-and-after numbers.

10. The tooling they will use, and whether it stays with you after the contract.

11. A pilot with fixed scope, fixed price and agreed success metrics, including security criteria.

Success metrics to put in any contract: deployment frequency, change lead time, run cost per application, defect rate after release, the share of legacy code retired, and the number of open high-severity security findings at each release. Good programs report these monthly, against a baseline taken before work starts.

FAQs

What do application modernization companies actually do?

They assess your legacy applications, choose a path for each one (rehost, replatform, refactor, rebuild or retire), do the engineering, and often run the result afterward. The better ones phase the work so each release pays for part of the next.

Does moving a legacy application to the cloud make it secure?

Not by itself. Rehosting moves the application onto newer infrastructure, but the vulnerabilities in its code, its login model and its logging gaps move with it. Security improves when the application is refactored, rebuilt or retired.

How long does legacy application modernization take?

A single application can take two to six months. An enterprise estate is usually a multi-year program delivered in waves of a few applications at a time.

How much do application modernization services cost?

It depends on scope and on who does the work. Published rates in this list range from under $25 per hour to $199 per hour, and project minimums from $5,000 to $100,000+. Large consultancies quote per program.

Is AI changing how modernization is done?

Yes. Every firm here now uses AI to read old code, map dependencies, and draft converted code. Human review is still required; AI-converted code still needs security testing, and the vendor speed claims above are self-reported.

Bottom line

Legacy applications that cannot be patched or monitored are one of the clearest security risks most organisations carry, and modernizing them is the only lasting fix. If you are a large enterprise with a mainframe estate, IBM Consulting and Accenture have the depth. If engineering quality is the main test and the budget is there, EPAM leads on buyer ratings. If published security assurance is your first filter, Persistent Systems documents the most. If you are a mid-size company that needs a phased start and a clear handover, look at firms that let you test a team before committing.

For mid-market and enterprise teams that want legacy application modernization with an API-first augmentation approach, a two-week paid trial and full IP transfer, CISIN offers modernization and custom software builds priced from $10K to $50K for basic scope up to $200K+ for enterprise programs, delivered by an ISO 27001-certified, CMMI Level 5 team.