An Overview of the Top Software Modernization Companies

62% of business leaders at mid-sized and large companies believe parts of their business-critical applications are already so outdated that they no longer meet current requirements and have to be renewed. The same study indicates that 83% of companies plan to increase their IT modernization budget in 2026.

To handle the complexities of modernization, such as undocumented legacy code, risky data migrations, and outdated frameworks, many companies refer to vendors that provide the necessary technology expertise. But the domain is crowded, and finding a reliable company with expertise in your tech stack or ready to adjust to your specific modernization needs can be challenging.

This article covers ten software modernization companies worth adding to your shortlist for 2026-2027, along with the technology stacks and modernization types they actually handle. It also explains how we selected them and helps you match your own legacy system to the type of vendor that fits it best.

McKinsey found that more than 90% of software teams use AI for refactoring, modernization, and testing, saving about six hours per week. AI has noticeably sped up modernization, with top-performing software organizations improving time to market by up to 30%, according to the same McKinsey article. Current tooling can map a legacy codebase, translate it, and generate tests in days. What it cannot do is decide which of those outputs you are allowed to trust.

That gap is measurable. Code produced by AI models can contain 1.7 times as many bugs as human-written code, and the real number depends heavily on how complex the existing codebase is. On a system with no current documentation, your own team often cannot tell a faithful translation from a plausible one.

A modernization company supplies the layer around the tooling: a technical audit before the proposal, behavioral checks between the old system and the new, review gates at every stage, and a named engineer accountable for each decision. That structure follows the principles of Leobit’s AI-native SDLC, which applies AI across every phase of a project while keeping human specialists in charge of critical decisions and validation.

To build this shortlist, we reviewed 59 vendors that run a named modernization or reengineering practice.

Our research covered company websites, profiles on review platforms like Clutch, GoodFirms, and G2, independent analyst coverage of the application modernization market, cloud and platform partner directories, and publicly available case studies.

Companies made the list when they met the following criteria:

• A named modernization or reengineering practice, rather than modernization listed as one line in a services menu
• Named legacy stacks and named modern targets, published on the company’s own site
• Public case studies for completed modernization projects
• Platform partnerships that match the target stack, such as Microsoft Solutions Partner status for Digital & App Innovation, or an the participation in Claude Partner Network
• Independent validation, such as verified client reviews
• A stated assessment or discovery phase before delivery begins
• Clear engagement models, from a one-off migration to a dedicated team that stays with the product

We excluded vendors whose modernization claims rested on self-reported figures with no case study or third-party source. We also excluded off-the-shelf solution providers with no delivery organization and legacy modernization companies that sell one modernization strategy as the answer to every legacy estate.

Using the criteria above, we built a list of the best software modernization companies for 2026-2027. Each entry covers the company’s background, modernization expertise, main industries, Clutch rating, and the type of buyer it suits best.

1. Leobit

Leobit is a full-cycle AI, web, mobile, and .NET development company with deep expertise in software modernization. The company runs a representative office in Austin, TX (USA) and development centers in Lviv (Ukraine), London (UK), Tallinn (Estonia), and Krakow (Poland).

Leobit has delivered 70+ legacy modernization projects and 15+ framework migrations, including .NET Framework to .NET, AngularJS to Angular, Xamarin to .NET MAUI, and monolith to microservices. These projects typically start with a comprehensive project discovery phase and cover architecture reengineering, cloud migrations, performance optimization, and technical audits. The vendor also rebuilds legacy solutions on modern technology stacks, preserving core functionality while adding new features.

What sets Leobit apart is its AI-native approach, which integrates AI across project phases. During software modernization, specialists use AI-assisted legacy code analysis and automated checks to compare the old and new systems, verifying that the new solution preserves the original behavior. The vendor serves multiple industries, including fintech, healthcare, real estate, sportstech, insurtech, logistics, edtech, etc.

Leobit holds Microsoft Solutions Partner designations for Digital & App Innovation and for Data & AI and is also certified in the Claude Partner Network, Anthropic’s partner program. The vendor holds ISO 9001:2015 and ISO 27001:2022 certifications and ISTQB Platinum Partner status, which matters because test coverage is what proves a modernized system still behaves like the one it replaced.

On Clutch, Leobit holds a 5/5 stars rating across 63 reviews. Reviewers emphasize their efficiency with the timeliness most often. Many positive reviews also mention the vendor’s proactive communication, technology expertise, and flexibility.

Leobit is a strong fit for mid-market and growth-stage product companies modernizing a .NET, web, or mobile platform that has to keep running while it changes.

Essensys is a Romanian software company founded in 2005, with offices in Bucharest and Brasov and a team of roughly 100 people.

Enterprise application modernization is Essensys’s largest service area, followed by custom software development, with most modernization projects centered on Microsoft Azure. The company has hands-on experience migrating legacy applications to Azure, particularly for clients in the fintech and public sectors, helping them update their technology infrastructure while maintaining business continuity. Essensys also brings specialized experience in modernizing navigation systems, extending its capabilities to complex, industry-specific software.

Essensys has a 4.9/5 stars rating across 24 reviews on Clutch. Scheduling is its highest-rated area, with clients frequently praising on-time delivery, organized project management, and adaptability to changing requirements. However, some reviews raise concerns about how the company handles revisions and communicates project updates.

Essensys is a strong fit for European mid-market businesses looking for enterprise application modernization companies that can upgrade business-critical systems.

3. Test Double

Test Double is a US software consultancy founded in 2011 and headquartered in Claymont, Delaware.

The company offers legacy software modernization, product performance turnaround, and Ruby software upgrades. It focuses on large modernization projects for enterprise customers like Gusto, a major US provider of payroll and HR management software.

Test Double typically embeds its software modernization consultants with the client’s own engineers. They act as solution architects and knowledge holders, passing what they learn about the system to the client’s team. This is why Test Double puts training for clients’ in-house teams at the center of its approach. The company’s primary industries include retail, automotive, energy and natural resources, and education.

On Clutch, Test Double holds a 4.8/5 stars rating across 6 reviews. Reviewers describe engineers who integrate quickly and work as an extension of their team. Still, some clients would want the company to spend more time teaching their in-house specialists.

Test Double is a strong fit for US companies whose own engineers will keep owning the codebase and need senior help modernizing it in place.

4. Trigent Software

Trigent Software is an experienced software development vendor founded in 1995. The company is headquartered in Southborough, Massachusetts, and has a delivery center in Bengaluru, India.

Software modernization is one of the company’s core offerings. In particular, Trigent Software has deep expertise in modernizing legacy enterprise solutions. The company also specializes in developing AI agents, built around its ArkOS platform. Manufacturing dominates the client base by a wide margin, followed by supply chain and logistics, medical, insurance, and automotive. The company holds ISO 9001 and ISO 27001 certifications that confirm its focus on quality in software modernization and development projects.

On Clutch, Trigent Software holds a 4.8/5 stars rating across 57 reviews. Timely delivery is the most mentioned strength, along with professionalism and technical knowledge in AI and cloud work. However, several reviewers said initial scoping and requirements gathering could be more thorough, which led to scope changes later. Some customers also mention time zone and language friction, but note that the team works to manage it.

Trigent Software is a strong fit for companies that need a large engineering team for modernization work from a long-established vendor.

5. Briebug

Briebug is a US consultancy founded in 2009, based in Littleton, Colorado. It is one of the application modernization companies that emphasize the seniority of a relatively small engineering team.

Briebug runs US-based Angular teams that handle Angular modernization and AngularJS migration for business-critical front ends, primarily in regulated industries like telecommunications, IT, and healthcare. The vendor’s portfolio also includes projects in the arts and entertainment domain. Beyond software modernization, Briebug offers compliance consulting and helps clients update their systems to meet changing security and privacy requirements.

On Clutch, Briebug holds a 4.9/5 stars rating across 8 reviews. Reviewers cite on-time delivery, clear communication, and expertise in modern frameworks among the vendor’s core strengths. There are minor claims regarding early communication issues that the company manages to solve through effective project management practices.

Briebug is a strong fit for organizations with a business-critical AngularJS or legacy Angular front end that want a small, senior, US-based team.

6. Bellwood

Bellwood is a boutique firm founded in 2019, headquartered in Atlanta, Georgia, with an office in Toronto, Canada. It is also a small team with a strong focus on its specialists’ seniority.

Bellwood core services include software modernization, system integration, and data migration. The vendor focuses on replacing old systems completely instead of extending them. Data migration matters just as much, because replacement projects usually fail on the data, not the application. Most clients come from domains like financial services, healthcare, and manufacturing. Others come from retail, real estate, and hospitality.

Clutch named Bellwood a Top App Modernization Service in the United States for 2026. The firm also holds Clutch’s 2026 Top Software Developers and Top Web Developers awards for Atlanta. On Clutch, it holds a 4.9/5 stars rating across 15 reviews. Timeliness is the most mentioned strength, followed by proactive communication, honesty, and attention to detail. A few reviews, however, mention issues with deadline extensions as an area for improvement.

Bellwood is a strong fit for smaller US organizations replacing a system rather than patching it, who want a boutique team.

7. Blackburn Labs

Blackburn Labs was founded in 2015 and works from Providence, Rhode Island, and Boston, Massachusetts. It is one of the legacy software modernization companies with a strong focus on the North American market.

The vendor offers modernization, custom software development, and business intelligence services. The company has an established “Innovate, Architect, Build” model applied to legacy software modernization projects. Blackburn Labs provides a multifunctional team that can both upgrade a legacy application and improve its analytical capabilities by integrating a reporting layer. It is relevant to many modernization projects because legacy reporting is often where the undocumented business logic actually lives. The company’s primary industries are healthcare, real estate, and edtech. Blackburn Labs also focuses on cooperation with startups and emerging businesses.

On Clutch, Blackburn Labs holds a 5/5 stars rating across 16 reviews. Communication and transparency are the most mentioned strengths, along with on-time delivery, the ability to pick up complex projects mid-stream, and repeated testing rounds before release. Reviews that suggest improvements mention communication and accessibility problems, mostly from non-technical clients.

Blackburn Labs is a strong fit for US small and mid-sized organizations that need a modernization project and a data or BI layer handled by the same team.

8. Xebia

Xebia is an IT consultancy headquartered in Amsterdam, Netherlands. Founded in 2001, it is a large software development vendor with a team of over 5,000 specialists. Xebia has offices across 11 locations in Europe, the USA, the UAE, and India.

The company offers software modernization services that cover strategic planning, cloud and data modernization, legacy and application modernization, and product re-architecture. Its application modernization approach starts with an assessment, then picks a path. The most common approaches handled by the company include rehosting to Azure or AWS, refactoring for Kubernetes, rearchitecting into microservices, or retiring outdated components. The vendor also built an AI-assisted tool for assessing legacy codebases on Amazon Bedrock and SageMaker.

Xebia was named Google Cloud Partner of the Year for Benelux in 2026 and was a finalist for the 2025 Microsoft Partner of the Year Award in the Accelerate Developer Productivity category. It also holds GitHub Global Partner of the Year recognition for 2024 and 2025, along with GitHub Global Security Partner of the Year for 2024.

The company holds a 4.7/5 stars rating across 7 reviews on Clutch. Reviewers mention flexibility, quality of work, timeliness, and unique expertise. There are still some suggestions for the team to improve their approach to problem framing.

Xebia is a strong fit for buyers who want a cloud-first modernization partner, especially on AWS, with a European delivery base.

9. Simform

Simform is a custom software development and modernization company founded in 2010. The vendor is headquartered in Orlando, Florida, and lists nine further offices, including Los Angeles, Chicago, San Francisco, Austin, New York, Vancouver, Dubai, and Ahmedabad. The company also has a large team of 1,000+ specialists.

Simform primarily specializes in enterprise solutions. The company runs enterprise app modernization and can migrate large-scale software solutions to the cloud. The company has deep expertise in developing and upgrading CRM and ERP systems. Simform also offers staff augmentation for software reengineering projects. The vendor’s clients come from a variety of industries, with education, real estate, fintech, business services, and IT being the most common ones.

On Clutch, Simform holds a 4.8/5 stars rating across 89 reviews. Timely delivery and communication are the most mentioned strengths, followed by quality of work and project management. Several clients asked for more end-user documentation and onboarding material, and some reported timelines shifting as requirements changed.

Simform is a strong fit for enterprise clients that want a large multi-office vendor with a heavily reviewed track record.

10. BairesDev

BairesDev was founded in 2009, is headquartered in San Francisco, California, and has offices in Buenos Aires, São Paulo, Mexico City, Bogotá, and Barcelona.

The vendor supplies nearshore engineers from across Latin America, with full US time-zone overlap. Its legacy application migration practice covers the full path: code assessment, data migration, rehosting, refactoring, replatforming, API integration, and decommissioning with data archiving. The company helps clients choose between different modernization strategies and builds compliance with GDPR, HIPAA, and PCI DSS into the process. Clients can engage through staff augmentation, a dedicated team, or full outsourcing. BairesDev is Microsoft-certified, with a .NET and Azure practice, and holds ISO 27001.

On Clutch, BairesDev holds a 4.9/5 stars rating across 63 reviews. Quality of work and timely delivery are the most commonly cited strengths. On improvements, a few clients note language barriers and ask for clearer explanations of technical concepts, and some report early developer turnover.

BairesDev is a strong fit for US companies that need to add modernization engineering capacity quickly and keep it within their own working hours.

The ten companies presented on this list cover different modernization needs, industries, and business models. Some run multi-thousand-person cloud practices that rehost and rearchitect enterprise estates. Others are boutique teams of senior engineers who replace one system properly and move its data without losing any. A few embed consultants alongside your own developers and hand the knowledge back, and one supplies nearshore capacity inside your working hours.

Whether you need to migrate your solution to a new framework, upgrade parts of the existing system, or rebuild your legacy software completely, Leobit can help. Contact us to discuss your modernization needs.