Legacy software modernization is the work of taking an application that still runs the business (often a monolith on aging servers, sometimes COBOL on a mainframe) and rebuilding, re-platforming, or moving it so it can run and change safely in the cloud. Most enterprises do not fail at this because the target cloud is wrong. They fail because the partner they hired was good at one half of the job and weak at the other: strong at code but weak at operations, or the reverse.
We compared five firms that do both halves. We looked at how each one handles the old code, how it builds the delivery pipeline afterward, which cloud partner tiers and certifications it actually holds, how it prices work, and where it is the wrong pick.Â
The cloud side is no longer exotic. The latest CNCF annual survey reports that 82% of container users now run Kubernetes in production, so the hard part of a cloud migration today is usually the legacy code and the team habits around it, not the platform.
What legacy modernization and cloud migration actually include
A legacy modernization project usually follows one of a few paths. Rehosting moves the application to cloud servers with few code changes (often called lift and shift). Re-platforming changes the runtime or database but keeps the core logic. Refactoring or re-architecting breaks the application into smaller services that can be deployed on their own. Replacing means retiring it for a commercial product.
A few terms come up in every proposal, so here is what each one means in plain words:
- CI/CD (continuous integration and continuous delivery): an automated pipeline that builds, tests and ships every code change, so releases happen in small steps instead of one big risky weekend cutover at the end of a cloud migration. At enterprise scale, look for pipelines with automated security scans and rollback built in.
- Infrastructure as Code (IaC): servers, networks, and permissions written as code files (Terraform, Pulumi or AWS CloudFormation are common tools), so environments can be rebuilt the same way every time and reviewed like any other change.
- Multi-cloud and hybrid cloud: running workloads across more than one provider (AWS, Microsoft Azure, Google Cloud) or across a provider and your own data center. It adds options but also adds billing and security work.
- DevSecOps: DevOps with security checks built into the pipeline from the start, instead of a separate review at the end.
Public-sector guidance says the same thing private buyers learn the hard way. The federal Cloud Smart strategy notes that “Migration to the cloud may require decommissioning legacy systems that have been in use for many years,” which is why a cloud migration plan should start with an application inventory, not a server count.
How we ranked these legacy software modernization companies
We scored each firm on five things, in this order of weight:
- Legacy depth: does it publish a method for old code (reverse engineering, mainframe work, incremental refactoring), or does it only talk about new cloud builds?
- Pipeline and operations: CI/CD, IaC and DevSecOps as part of the delivery, not an add-on.
- Verifiable credentials: cloud partner tiers and competencies we could confirm on the firm’s own pages, plus process certifications such as CMMI and ISO 27001.
- Price transparency: a published rate, project range or at least a clear pricing model.
- Fit: the size of buyer each firm is set up to serve well.
Ratings come from Clutch or Gartner Peer Insights as listed on those sites when we checked them in October 2026. Every entry, including the first, includes a limitation.
The 5 best legacy software modernization and cloud migration companies
1. Cyber Infrastructure (CISIN)
Best for: mid-market and enterprise IT teams that want legacy software modernization and cloud migration handled by one vendor, with a trial period before they commit to a long contract.
Cyber Infrastructure (CISIN) is a custom software development and IT services company, founded in 2003, whose service list covers legacy application modernization, cloud adoption and migration, DevOps, DevSecOps and infrastructure as code across AWS, Microsoft Azure and Google Cloud.Â
In practice, you work with a POD team (CISIN’s term for a small cross-functional unit), and the one that matters here is its DevOps and Cloud-Operations Pod. Staff augmentation pods scale from 2 to 20 engineers.
CISIN’s published migration roadmap for Java estates runs in four steps: discovery and a TCO/ROI assessment, a pilot that sets up CI/CD and Kubernetes, incremental refactoring, then cost governance. Its own guidance names the biggest mistake as lift-and-shift without refactoring, and we agree with that. On cost, CISIN reports from its 2025 internal data that clients with a dedicated FinOps (cloud cost management) practice cut cloud spend by an average of 22% within 12 months. That is a self-reported figure, not an audited one.
- Scope: legacy re-engineering, cloud migration, CI/CD, IaC, DevSecOps, cloud monitoring and support
- Credentials: CMMI Level 5, ISO 9001:2015, ISO 27001, Microsoft partner; 1000+ employees and 5000+ completed projects (company-reported)
- Rating: 4.9 on Clutch (36 reviews)
- Pricing: published custom software tiers of $10K to $50K (basic), $50K to $200K (medium) and $200K+ (enterprise); Clutch lists a $5,000+ minimum and rates under $25 per hour. Engagements run as time and materials, fixed price for defined scope, or project pods. A two-week paid trial, free replacement of any engineer who does not perform, and full IP transfer on payment are standard terms.
- Not good for: buyers whose procurement requires a published AWS or Google Cloud partner tier. CISIN’s public pages list a Microsoft partnership but no AWS or Google tier, and its modernization case studies are mostly short qualitative summaries rather than dated before-and-after metrics.
2. EPAM Systems
Best for: large banks, insurers and asset managers that need a cloud migration partner with deep financial-services history and AWS funding experience.
EPAM is a digital engineering and consulting firm, founded in 1993 in Princeton, New Jersey, with more than 62,850 employees across 55+ countries and regions. For modernization buyers, its draw is scale plus financial-services depth.Â
EPAM says 7 of the 10 largest investment banks rely on it, and 3 of its 5 largest clients are in financial services. That answers a question many buyers ask: who has done large migrations in regulated finance?
The working model is assessment first. EPAM’s migVisor tool scans on-premises database estates, and the firm claims assessments run up to 3x faster with it. One published insurance case reports that AWS Migration Acceleration Program (MAP) funding covered 70% of migration costs, with zero unplanned outages.
- Scope: application and database modernization, cloud migration, platform engineering, data and AI
- Credentials: AWS Premier Tier Services Partner, with more than 6,000 AWS-certified experts
- Rating: 4.9 on Gartner Peer Insights (88 ratings, custom software development services)
- Pricing: Clutch lists $150 to $199 per hour with a $100,000+ minimum project
- Not good for: companies with one or two applications to move. The minimum project size and senior rate card make it hard to justify below a multi-application program.
3. N-iX
Best for: mid-size and large companies that want an engineering-led cloud migration team with formal AWS competencies at a lower rate than the big consultancies.
N-iX is a software engineering company founded in 2002, with more than 2,400 engineers serving clients in Europe, the Americas, and APAC. It is a good example of a firm whose AWS credentials are specific rather than general: it holds AWS Premier Tier Services Partner status plus the AWS Migration and Modernization Competency and the AWS DevOps Competency, and it lists Microsoft and Google Cloud in its partner ecosystem.
From the buyer side, N-iX tends to staff dedicated teams that stay on through migration and the operations that follow, which helps when the CI/CD and IaC work needs to carry on after cutover. Much of its engineering capacity sits in Europe, so overlap with US business hours is partial.
- Scope: legacy application modernization, cloud migration, DevOps, data platform modernization
- Credentials: AWS Premier Tier; AWS Migration and Modernization, DevOps, and Data and Analytics competencies
- Rating: 4.8 on Clutch (35 reviews)
- Pricing: Clutch lists $50 to $99 per hour with a $100,000+ minimum project
- Not good for: teams that need full same-time-zone coverage in the US, or a small first project under the $100,000 floor.
4. Thoughtworks
Best for: engineering organizations that want to change how they build software while they modernize, as well as where it runs.
Thoughtworks is a technology consultancy founded in Chicago in 1993, with 10,000+ people in 47 offices across 18 countries. Its legacy modernization offer centers on AI/works, which it calls an agentic development platform, used to read old code, document behavior and support incremental rebuilding. For mainframes, it works with Mechanical Orchard on a phased approach that replicates system behavior before replacing it, which lowers the risk of a big-bang cutover.
The firm publishes concrete outcomes: 30 days saved in legacy code reverse engineering for a European automotive manufacturer, and 40% cost savings from a managed services transformation for a business management platform. Expect strong opinions on continuous delivery and team practices. That is useful if your internal team is part of the problem.
- Scope: legacy and mainframe modernization, platform engineering, CI/CD and delivery practices, data modernization
- Credentials: long-standing continuous delivery and DevOps practice; mainframe partnership with Mechanical Orchard
- Rating: 4.6 on Gartner Peer Insights (92 ratings, custom software development services)
- Pricing: quoted per engagement, usually as time and materials for blended senior teams; no public rate card
- Not good for: a straight rehost on a tight budget. You would be paying for practice change you did not ask for.
5. Accenture
Best for: global enterprises running a multi-year modernization program across hundreds of applications, several clouds and several countries.
Accenture is a professional services firm with about 799,000 employees and operations in 52 countries. For legacy modernization, it uses GenWizard, a generative AI platform for refactoring, re-platforming, and re-architecting applications, plus reverse engineering that turns old code into documentation for a living knowledge base. This is the vendor whose cloud migration programs come with a full governance office, change management, and multi-provider partnerships.
Scale is the reason to hire Accenture and the reason to hesitate. A mainframe exit spanning several business units and three hyperscalers is the kind of work it is built for. A single ERP integration is not.
- Scope: application rationalization, mainframe and legacy modernization, multi-cloud migration, managed operations
- Credentials: publicized partnerships with Google Cloud and AWS; GenWizard AI platform for modernization
- Rating: 4.5 on Gartner Peer Insights (113 ratings, public cloud IT transformation services)
- Pricing: enterprise programs priced under statements of work, usually multi-year; no public rate card
- Not good for: mid-size companies. Smaller accounts often get less senior attention, and governance overhead can outweigh the work.
How to choose a modernization partner for your cloud migration
Start with the application, not the vendor. List each system, what it does, who changes it, and what breaks if it goes down. Then match the work to the firm.
If your estate is mostly .NET and SQL Server, ask for a Microsoft partnership and proof of Azure migrations. Teams going to AWS should ask which AWS competencies the firm holds and whether it can apply for MAP funding on your behalf, which EPAM and N-iX both describe. When the system holds federal data, the vendor and the target cloud services need to fit FedRAMP. Note that, per the FedRAMP program rules, “A FedRAMP authorization is not an endorsement of a product or service,” so it is a floor, not a quality score.
On engagement models, there are three common ones:
- Staff augmentation: you manage the engineers; the vendor supplies them. Cheapest and most flexible, but the plan is on you.
- Managed DevOps or cloud operations: the vendor runs pipelines and environments after migration under a service agreement.
- Project-based: a defined scope with milestones, sometimes at a fixed price. This works best when the legacy system is well documented.
For ROI, measure lead time for changes, deployment frequency, change failure rate and time to restore service (the four DORA metrics), plus monthly cloud spend per application. Ask every shortlisted firm for those numbers from a past client, before and after, with a date. A vendor that can only show a logo wall has not measured its own legacy software modernization results.
When you should not hire a firm at all
Build in-house if you already have a platform team that owns CI/CD and IaC, the legacy system is small, and the main gap is a few months of focused refactoring. Outside firms add the most value when the old code is poorly documented, the cloud skills are missing internally, or a deadline (an expiring data center lease, an end-of-support date) makes hiring too slow.Â
The CNCF survey also found that “cultural changes with the development team” is the top challenge, cited by 47% of respondents. No vendor fixes that for you, so plan for training regardless of who you hire.
Frequently asked questions
How much does legacy software modernization cost?
It depends on the number of applications and the path you pick. Published reference points from the firms above range from custom software tiers of $10K to $200K+ (CISIN) to $100,000+ project minimums (EPAM and N-iX). Mainframe exits at large enterprises are usually multi-year programs priced by statement of work.
Which cloud certifications matter most when picking a cloud migration company?
Partner tier (for example AWS Premier Tier) shows commercial scale. Specific competencies, such as the AWS Migration and Modernization Competency, show audited delivery in that area. Process certifications such as CMMI Level 5 and ISO 27001 show how the firm runs projects and protects data. Ask for all three and confirm them on the vendor’s own pages or the cloud provider’s partner directory.
Should we pick staff augmentation or managed DevOps after migration?
Pick staff augmentation if you have a strong engineering lead who will own the roadmap. Pick managed DevOps if nobody internally will own pipelines and on-call after cutover, because a migrated system without an owner drifts back into legacy within a year or two.
Is lift and shift ever the right first step?
Yes, when a deadline forces it, for example a data center exit. Treat it as step one of a cloud migration, with refactoring budgeted afterward. Rehosting alone usually moves the cost problem to a new bill.
Bottom line
All five firms can move legacy systems to the cloud. The choice comes down to scale, budget and how much proof you need on paper. EPAM and Accenture suit large regulated programs with large budgets. N-iX gives strong AWS credentials at mid-range rates.Â
Thoughtworks is the pick when your delivery practices need to change along with the code. For mid-market and enterprise IT leaders who want legacy software modernization and cloud migration under one CMMI Level 5 contract, with a DevOps and Cloud-Operations Pod, a two-week paid trial and published project tiers starting at $10K to $50K, CISIN is the first call we would make.