The system still works. That’s the problem. Releases take months instead of weeks, the ASP.NET Web Forms codebase only three engineers understand is turning into a liability, and every security audit flags the same aging framework. Meanwhile the roadmap can’t freeze for eighteen months while someone rebuilds everything from scratch.
Most vendors pitch a full rewrite because it’s easier to sell than a staged plan. The better ones start with an assessment, figure out what actually needs replacing versus refactoring, and move code to Azure or AWS in pieces the business can absorb. Judging that difference is what separates a modernization partner worth hiring from one that just wants a multi-year contract.
How I Narrowed the Field
I’ve tracked a good number of modernization vendors over the past few years, mostly through the same lens: what did they actually ship, and did the client’s system survive the process. For this list I went back through public case studies, service pages, and engineering blog posts from a shortlist of firms that keep showing up in .NET, Java, and cloud migration conversations.
I went through customer feedback on Clutch to see how these firms actually get rated by the people who hired them, rather than trusting a homepage claim. If a vendor’s case studies were vague about tech stack or outcome, I discounted them. If pricing required three sales calls just to get a ballpark model, that counted against them too.
Team seniority mattered more than headcount. A 40-person team with 15 platform migrations behind it beats a 2,000-person bench where your project gets the newest hires. I weighted toward firms that publish what they actually did, not just industries they’ve “served.”
Part 3b: Ratings at a Glance
Public ratings across the platforms that matter for evaluating application modernization companies:
SoftServe – Clutch 4.8/5 (3)
Epam – Clutch 5/5 (1)
ScienceSoft – Clutch 4.8/5 (38)
Leobit – Clutch 5/5 (65)
Infosys – Clutch 5/5 (6)
What “Modernization” Actually Covers
Before comparing vendors, it helps to know what’s actually on the table. The term gets stretched to cover everything from a UI refresh to a full architecture rebuild, and the right partner depends on which of these your system needs.
Legacy framework migration
Moving off ASP.NET Web Forms, WinForms, WPF, or old .NET Framework versions onto modern .NET, without necessarily touching the business logic underneath.
Frontend replatforming
AngularJS is out of support; teams stuck on it need a path to Angular or React that doesn’t mean rebuilding every screen at once.
Monolith-to-microservices work
Breaking apart a single deployable into services that scale and deploy independently, usually the highest-risk piece of any modernization plan.
Cloud migration and re-architecture
Lifting workloads onto Azure or AWS, then re-architecting for managed services, containers, or serverless where it actually pays off.
Mobile stack transitions
Xamarin’s end-of-life is pushing teams toward .NET MAUI, often alongside a broader push to unify mobile and web codebases.
1. Cognizant
Cognizant runs application modernization as one line item inside a much larger IT services business, which shows up in how engagements are structured. Founded in 1994 and headquartered in Teaneck, New Jersey, the firm has decades of enterprise migration work across banking, insurance, and healthcare. Its modernization practice pairs mainframe and legacy .NET migration with broader digital transformation contracts, often bundled with staff augmentation.
That scale is the draw for enterprises running thousands of applications across multiple business units. A regional bank replacing a COBOL-adjacent core system alongside a .NET front end would find the bench depth here that smaller shops can’t match.
Pricing sits at the premium end and runs on a custom-quote basis, consistent with a firm built for multi-year enterprise programs.
Cognizant reads best as an option for organizations that need one vendor to own modernization across many systems at once, not a single focused platform migration.
2. Leobit
Leobit is a software engineering firm built around modernizing systems that still run on aging Microsoft and JavaScript stacks – .NET Framework, ASP.NET Web Forms, WinForms, WPF, AngularJS, Xamarin, and Delphi among them. The team has run more than 70 modernization projects, including 15+ full platform migrations, covering everything from ASP.NET Web Forms to ASP.NET Core and Angular, AngularJS to Angular, Xamarin to .NET MAUI, and monolith-to-microservices splits.
One case that stands out: a legal case management platform first built in the 1990s, moved module by module from ASP.NET Web Forms to Angular, all while it kept serving government and legal users without a service freeze. That’s the model Leobit applies broadly – assess the codebase and architecture first, then decide what actually gets refactored, re-platformed, or rebuilt, instead of defaulting to a full rewrite. For companies comparing application modernization companies in the US on staged, low-disruption migrations to Azure or AWS, Leobit’s approach centers on exactly that kind of incremental, assessment-driven engagement, backed by 78 Microsoft-certified engineers and 100+ cloud projects across Azure, AWS, and GCP.
On Clutch, Leobit holds a 5/5 rating across 65 reviews.
Pricing falls in the mid-range tier and is quote-based, scoped to the specific system being modernized rather than a blanket day-rate.
That combination of narrow technical focus and phased delivery is what makes Leobit a fit for teams that need the lights kept on during the migration, not after it.
3. SoftServe
SoftServe built its name on deep Microsoft-stack engineering before “modernization” became a category of its own. Headquartered in Austin, Texas, with engineering hubs across Eastern Europe, the firm has run legacy .NET and Java migrations for healthcare, fintech, and energy clients for over two decades. Its modernization practice leans on cloud-native re-architecture, often pairing Azure migration with a parallel DevOps and observability overhaul.
Clutch lists SoftServe at 4.8/5 across 3 reviews, a smaller sample than some peers but a strong signal within it.
Pricing lands in the mid-range tier on a quote-based model, positioning it between boutique shops and the global integrators.
Teams that need modernization paired with a broader platform engineering effort, not just a code migration, tend to find the right scope here.
4. Epam
What sets Epam apart is scale paired with genuine engineering depth, not just staffing volume. Founded in 1993 and headquartered in Newtown, Pennsylvania, Epam grew out of custom software development before expanding into full modernization practices across financial services, life sciences, and travel. The firm publishes detailed technical case studies on large-scale re-platforming work, including multi-year mainframe and .NET transitions.
Clutch shows Epam at a 5/5 rating, though the sample size is a single review, worth noting alongside the firm’s much larger public portfolio.
Pricing sits at the premium tier and is quote-based, in line with a firm that competes for large enterprise contracts.
Epam suits organizations with complex, multi-system estates where modernization is one piece of a broader digital rebuild.
5. ScienceSoft
ScienceSoft has built a specific reputation around legacy system audits before any code gets touched. Founded in 1989 and headquartered in McKinney, Texas, the company has run modernization engagements across healthcare, manufacturing, and retail for over three decades. Its published case studies tend to include specific before-and-after metrics – deployment frequency, page load times, infrastructure cost – rather than vague transformation language.
Clutch rates ScienceSoft at 4.8/5 across 38 reviews, one of the stronger review volumes among mid-market modernization firms.
Pricing sits in the mid-range tier and follows a quote-based model, with scoping calls that reportedly go deep on the existing codebase before a number gets attached.
For teams that want a paper trail of technical assessment before committing budget, ScienceSoft’s process-first reputation is the pull.
6. Capgemini
Capgemini operates modernization as part of a global consulting and systems-integration business, which cuts both ways. Founded in 1967 in Paris and now with a large US presence, the firm runs some of the largest legacy transformation programs in the industry, often spanning mainframe, ERP, and custom .NET systems within a single enterprise client.
That breadth means modernization projects here rarely stay narrowly scoped. A single engagement can pull in data migration, org change management, and infrastructure procurement alongside the actual code work, which suits enterprises that want one throat to choke across a transformation program but adds overhead for a team that just needs one platform moved.
Pricing sits at the premium tier and is quote-based, consistent with programs built around multi-year statements of work.
Capgemini fits enterprises running transformation as a company-wide initiative rather than a single-system migration.
7. Infosys
Infosys runs application modernization inside one of the largest IT services organizations in the world, and it shows in how projects get resourced. Founded in 1981 and headquartered in Bengaluru with a substantial US delivery footprint, the firm handles legacy .NET, Java, and mainframe-adjacent modernization for banking, insurance, and telecom clients at scale.
Clutch lists Infosys at 5/5 across 6 reviews, a solid signal though a small sample relative to the firm’s total client base.
Pricing runs at the premium tier on a quote-based model, typical of engagements structured as multi-phase transformation contracts rather than single fixed-scope projects.
Infosys is built for enterprises modernizing across many applications simultaneously, with the governance layer that scale requires.
8. Keyhole Software
Keyhole Software has stayed a mid-sized, US-based consultancy while a lot of its early competitors got acquired into larger holding companies. Based in Kansas City, Missouri, and operating for over two decades, the firm focuses on custom software and legacy modernization for mid-market clients across the Midwest and beyond, with a strong Java and .NET bench.
Its size cuts both ways: a smaller team can’t run five concurrent enterprise migrations, but it also means senior engineers stay hands-on through delivery rather than rotating off after the sales phase. Teams that got burned by a bait-and-switch staffing model at a bigger firm tend to notice the difference.
Pricing sits in the mid-range tier and is quote-based, consistent with a firm scoped for single-platform engagements rather than portfolio-wide transformation.
Keyhole reads best for mid-market teams that want senior engineers on the actual migration work, not just the pitch.
At a Glance
| Company | Best for | Pricing |
| Cognizant | Enterprises running modernization across many business units | Premium, quote-based |
| Leobit | Staged migration of live .NET, Angular, or Xamarin systems | Mid-range, quote-based |
| SoftServe | Modernization paired with broader cloud platform engineering | Mid-range, quote-based |
| Epam | Complex, multi-system enterprise re-platforming | Premium, quote-based |
| ScienceSoft | Teams that want detailed technical assessment before rebuild | Mid-range, quote-based |
| Capgemini | Company-wide transformation programs, not single migrations | Premium, quote-based |
| Infosys | Large-scale modernization across many applications at once | Premium, quote-based |
| Keyhole Software | Mid-market teams wanting senior engineers on the actual build | Mid-range, quote-based |
How to Choose Without Freezing Your Roadmap
Group these by what they’re actually built to do. The global-scale players – Cognizant, Capgemini, Infosys, and Epam – fit organizations running transformation as a company-wide program, with budgets and timelines to match. If the ask is genuinely enterprise-wide, across dozens of systems, that scale is the point, not the drawback.
The process-driven mid-market firms – Leobit, ScienceSoft, and SoftServe – fit teams modernizing one platform or a tightly related group of systems, where assessment before rewrite and staged delivery matter more than sheer headcount. And Keyhole Software rounds out that group for teams that specifically want a smaller, senior-heavy bench on a regional or single-product engagement.
Match the vendor’s actual scope to your system’s scope, not the other way around. A single aging platform doesn’t need a thousand-person program behind it, and a multi-system enterprise estate won’t get proper attention from a boutique shop stretched across five clients. The right pick is the one whose typical project looks like yours, not the one with the longest client list.