Updating an old system is rarely just about new code. The challenge is to keep the business running and keep the software familiar to end users while connecting legacy software with modern tools.
We selected seven companies that help businesses with legacy system integration and API transformation. Each service provider was selected based on their professional focus, expertise and ability to deliver real business value.
Corsac Technologies
Corsac Technologies is a legacy system modernization and integration partner with over 18 years of experience. Corsac is aimed at uncovering the roots of technical stagnation and performing real system transformation, not just a needless code revamp. Before any work begins, the Corsac team carefully inspects an existing system to find outdated code, undocumented business logic, and other system bottlenecks. The Corsac team follows an incremental approach. They integrate with your CI/CD and act almost independently, freeing up your internal team resources. All changes made by Corsac are transparent and traceable, with your business goals in mind.
Reliqsy
Reliqsy is an AI-powered solution for software upgrades, helping companies accelerate the delivery of upgraded software. Reliqsy performs a thorough analysis of an existing system and generates modern, clean code to empower software to run more efficiently and scale with ease. The platform eliminates the key-person dependency and fragile manual turnarounds. This allows for the start of modernization without waiting months before engineers understand the undocumented logic of legacy software. Despite reliance on AI agents, Reliqsy follows a human governance approach, with all final decisions made after human review.
SmartBridge
Smartbridge is a legacy system modernization service provider founded in 2003. The company focuses on legacy system integration and API transformation, helping organizations link existing applications, databases, and platforms with modern software, cloud services, analytics tools, and customer-facing systems. Smartbridge’s services include data and analytics, digital innovation, automation, and AI implementation, and are focused on bringing measurable business value and a scalable digital solution.
The Smyths Group
The Smyths Group is one of the leading software and API modernization companies in the United States. The company focuses on uncovering the real cause of what is holding your business back and offering tailored modernization solutions to each customer. To make sure that products deliver result, company’s specialists developed a full-cycle approach, from creating optimization strategy to deployment with each step having clear deliverables. The Smyths Group guarantees a transparent process where your stakeholders stay updated and can track the progress.
Leobit
Leobit is an IT-service provider specializing in full-cycle software development and optimization services. Their team of dedicated professionals adapt the collaboration model to the needs of each business that is struggling with outdated systems. Leobit offfers tailored reengineering services, from seamless code migrations to complex architectural refinements. Instead of complex system redesign, they discover components to update to boost performance, scalability, and functionality. Additionally, the company offers high-quality UI/UX design services
Accenture
Accenture is a software modernization company that works in 120 countries and provides services to Fortune Global 100 та 500 companies. Their mission is to update old, complex systems without stopping daily operations. Their teams support legacy modernization, cloud migration, API development, system integration, data transformation, and mainframe updates. Accenture helps companies take a safe modernization route. Instead of replacing outdates systems all at once, they improve the parts that cause the most friction, connect older platforms with newer tools, and make data easier to access across the business.
Innowise
Innowise helps companies modernize older systems without from scratch rebuilt. Their team works with legacy software, API development, system integration, cloud migration, testing, and ongoing support. Innowise helps solve typical issues of legacy systems (vendor lock-in, high maintenance costs,manual workflows etc) by building custom APIs, integration layers, and modernization plans that connect legacy systems with CRMs, ERPs, SaaS tools, and cloud platforms. Innowise’s approach is to keep what works, improve what slows the business down, and make outdated systems easier to use, scale, and maintain.
Legacy system modernization does not have to mean starting from zero. In many cases, the smarter move is to look at what already works, find the parts that slow the business down, and improve them step by step. The right modernization partner, will not just update the code. They will help your business move forward while keeping the systems you still rely on stable.
