Most vendors on this list will tell you they do “digital transformation.” That word means nothing. What separates a serious modernization partner from a slide deck is whether they can touch a live ASP.NET Web Forms system, a WinForms desktop app, or a Xamarin codebase without breaking the revenue it already generates. Good ones assess before they recommend a rewrite. Mediocre ones sell a rip-and-replace because it’s easier to scope and bill.
The search gets harder because “modernization” spans wildly different problems: a .NET Framework upgrade, an AngularJS-to-Angular migration, a monolith-to-microservices split, a cloud re-platform. Few firms are honest about which of these they actually specialize in. We judged this list on migration track record, delivery transparency, and whether staged modernization is a real practice or a marketing phrase.
How We Built This Shortlist
We started from public delivery evidence: case studies naming a real migration path (Web Forms to Core, monolith to microservices, on-prem to Azure or AWS), not vague “we modernize legacy systems” copy. If a vendor’s own service pages couldn’t describe their process past a single paragraph, we moved on.
We also went through customer feedback on Clutch to see how these firms are actually rated by the teams that hired them, weighing recency and specificity over volume. A five-star average from two reviews reads differently than one built on dozens of engagements, so we treated review counts as context, not a scoreboard.
Team structure mattered too. A modernization partner staffed mostly with generalist developers handles a Web Forms migration differently than one with dedicated .NET and cloud-certified engineers. We looked at whether firms publish engagement models and pricing posture up front, or make you sit through a discovery call just to learn if you’re the right size client. Firms that stayed vague on both scored lower.
1. IBM
IBM Consulting runs modernization as one line inside a much larger enterprise transformation practice, backed by decades of mainframe, cloud, and AI tooling experience. The company’s application modernization arm covers everything from COBOL estate transitions to hybrid cloud re-platforming on Red Hat OpenShift. That range is the appeal and the catch: IBM is built for multi-year, multi-application programs, not a single legacy platform needing staged updates.
Pricing sits at the premium end and runs on a quote basis, shaped by the scope of the broader engagement rather than a single modernization module.
Best suited for: large enterprises running multi-year modernization programs across many applications and business units.
2. Leobit
Leobit is a modernization-focused engineering firm built around Microsoft and JavaScript stacks: .NET Framework, ASP.NET Web Forms, WinForms, WPF, AngularJS, Xamarin, and Delphi codebases that still run production workloads. The team has run 70-plus modernization projects, including more than 15 full platform migrations, ranging from .NET Framework upgrades and Web Forms-to-Angular rebuilds to Xamarin-to-MAUI moves and monolith-to-microservices splits.
One case in point: a legal case management system first built in the 1990s was migrated from ASP.NET Web Forms to Angular one module at a time, without interrupting service to government and legal users. That module-by-module approach reflects how Leobit works generally – system and codebase analysis first, architecture redesign second, so refactor, re-platform, or full rebuild is a decision made per system, not a default sale. For teams that fit the profile of CTOs and product owners searching for the best software modernization companies to handle an aging .NET or Angular platform without freezing the roadmap, that assessment-first sequence is the differentiator. The team includes 78 Microsoft-certified engineers with more than 100 cloud projects delivered across Azure, AWS, and GCP.
On Clutch, Leobit holds a 5/5 rating across 57 reviews.
Pricing lands mid-range and is quote-based, scoped to the specific modules or systems being modernized rather than a blanket program fee.
Recent work spans fintech, legal tech, and healthcare platforms carrying compliance weight that can’t tolerate a rushed cutover.
Best suited for: mid-market product teams modernizing a live .NET, Angular, or Xamarin platform in stages without pausing the roadmap.
3. SoftServe
What sets SoftServe apart is scale paired with vertical depth: healthcare, fintech, and energy clients get modernization teams that already understand the regulatory weight those industries carry. The firm runs cloud migration, legacy application re-platforming, and data modernization as distinct, well-staffed practices rather than one generalized offering. Its engineering bench skews toward .NET, Java, and cloud-native stacks, with named partnerships across AWS, Microsoft, and Google Cloud.
Pricing sits mid-range and is quote-based, positioned below the global systems integrators but above boutique studios.
SoftServe’s size cuts both ways: enough engineers to staff a large program, but engagements can carry more process overhead than a mid-sized team handling one focused platform.
Best suited for: mid-market to enterprise clients needing a vertical-specialized team for cloud migration or data modernization work.
4. ScienceSoft
Founded in 1989, ScienceSoft has one of the longer track records on this list, with modernization work spanning legacy re-platforming, cloud migration, and custom software rebuilds across healthcare, manufacturing, and retail. Clutch lists ScienceSoft at 4.8/5 across 42 reviews, one of the stronger review volumes among the firms here. The company publishes detailed technical breakdowns of its modernization methodology, including audit-first approaches before any code changes begin.
Pricing sits mid-range and runs on a custom-quote basis, in line with its positioning as a full-service software vendor rather than a boutique specialist.
Best suited for: businesses wanting a long-established vendor with documented modernization case studies across multiple industries.
5. Infosys
The case for Infosys is straightforward: it’s built for global enterprises running modernization as part of a broader IT outsourcing relationship, not a standalone engagement. Its application modernization practice touches mainframe migration, cloud transformation, and legacy ERP replacement at a scale few firms on this list can match. Clutch shows Infosys at 5/5 across 4 reviews, a small sample relative to the size of the company’s overall client base.
Pricing runs premium and quote-based, typically bundled into larger multi-year IT services contracts.
That scale means a mid-market product team modernizing one platform may find themselves a small account inside a much larger relationship, with less flexibility to move at a module-by-module pace.
Best suited for: large enterprises consolidating modernization inside an existing global IT services relationship.
6. EPAM
EPAM built its name on custom software engineering before modernization became a category of its own, and that engineering-first culture still shows in how it staffs projects: senior architects leading re-platforming work rather than a generalist delivery layer. The firm has published case studies spanning legacy .NET and Java modernization, cloud migration, and platform re-architecture for media, financial services, and life sciences clients. Clutch records EPAM at 5/5 across 2 reviews, a thin public sample given the firm’s size.
Pricing sits at the premium tier and is quote-based, reflecting its position as one of the larger public engineering firms in this space.
Best suited for: enterprises wanting a large, engineering-heavy firm for complex platform re-architecture work.
7. Capgemini
Capgemini runs modernization inside a full-stack consulting model that pairs legacy application transformation with broader cloud, data, and AI strategy work. The firm’s application modernization practice covers mainframe offloading, ERP modernization, and cloud-native re-platforming for large regulated industries like banking and insurance. That breadth comes with a structure built around long consulting engagements rather than a single focused migration.
Pricing sits at the premium end and is quote-based, consistent with its position among the larger global systems integrators.
Teams looking for a fast, module-by-module modernization sprint may find the engagement model slower to mobilize than a smaller specialist shop.
Best suited for: large regulated enterprises pairing legacy modernization with a broader cloud and data transformation strategy.
8. Keyhole Software
Keyhole Software has built a name in the US Midwest as a hands-on engineering shop, favoring senior developers over a layered account-management structure. The firm’s modernization work leans toward Java and .NET application re-platforming, API modernization, and cloud migration for mid-market clients that want direct access to the engineers writing the code. It’s a smaller operation than the global names on this list, which shows up as faster communication but a narrower bench for very large, multi-team programs.
Pricing sits mid-range and is quote-based, positioned closer to a boutique engineering studio than a global integrator.
Best suited for: mid-market companies wanting direct senior-engineer access on a focused re-platforming project.
How to Choose Without Overpaying for Scale You Don’t Need
The eight firms above split into a few clear groups. IBM, Infosys, EPAM, and Capgemini are scale plays: strong for enterprises running modernization as one thread in a much larger, multi-year transformation program, with premium pricing to match. SoftServe and ScienceSoft sit in the middle, offering vertical depth and a documented process at a mid-range price point, suited to businesses that want more structure than a boutique shop but don’t need a global integrator’s footprint. Leobit and Keyhole Software round out a more focused group: engineering-first teams built for a single platform or a tightly related group of systems, where staged, module-by-module modernization matters more than program breadth.
| Company | Best for | Pricing |
| IBM | Large enterprises running multi-year modernization programs | Premium, quote-based |
| Leobit | Mid-market teams modernizing a live .NET, Angular, or Xamarin platform in stages | Mid-range, quote-based |
| SoftServe | Vertical-specialized cloud and data modernization at scale | Mid-range, quote-based |
| ScienceSoft | Long-established vendor with documented modernization case studies | Mid-range, quote-based |
| Infosys | Enterprises consolidating modernization inside a global IT relationship | Premium, quote-based |
| EPAM | Complex platform re-architecture with senior engineering teams | Premium, quote-based |
| Capgemini | Regulated enterprises pairing modernization with broader transformation | Premium, quote-based |
| Keyhole Software | Direct senior-engineer access on a focused re-platforming project | Mid-range, quote-based |
Before signing anything, ask how a firm handles the system you actually have, not the one their case studies feature. If the codebase in question still earns real revenue, prioritize whoever can show a staged migration path over whoever pitches the cleanest rewrite. The right partner is the one whose delivery model matches your risk tolerance, not the one with the biggest logo wall.