Legacy Software Modernization
Your legacy system works — but it is holding you back. We modernize it incrementally, without disrupting the business that depends on it.
Legacy systems are legacy because they work. They have been running your business for years, encoding institutional knowledge in their logic and handling edge cases that nobody fully remembers. The problem is not that they do not work — it is that they are increasingly expensive to maintain, impossible to hire for, and unable to integrate with the modern tools your team needs.
We approach legacy modernization as a careful, incremental process — not a reckless rewrite. We have migrated applications from PHP 5 to modern Node.js APIs, replaced jQuery monoliths with React frontends, extracted microservices from Rails monoliths, and moved on-premise Windows servers to cloud infrastructure. Each project maintained business continuity throughout.
We work with established businesses that know their legacy systems cannot last forever but need a partner who understands the risk involved in changing systems that work.
What You Get
Legacy System Audit
Comprehensive assessment of your current system: technology stack, dependencies, risk areas, business logic documentation, and modernization options with trade-off analysis.
Incremental Migration
Strangler fig pattern — new functionality is built in modern technology while the legacy system continues operating, gradually replacing it piece by piece.
API Extraction
Exposing legacy business logic through modern REST or GraphQL APIs, enabling new frontends and integrations without rewriting the core system.
Test Harness Creation
Building automated tests around legacy code that has none — characterization tests that capture existing behavior before any changes are made.
Containerization
Packaging legacy applications in Docker containers for consistent deployment, even before a full rewrite, making them cloud-ready and easier to operate.
Knowledge Recovery
Documenting undocumented business logic, creating architectural diagrams, and building a shared understanding of what the system actually does.
The Strangler Fig Approach
We rarely recommend a big-bang rewrite. Rewrites are expensive, risky, and historically have a high failure rate — the business keeps evolving during the 12-18 months it takes to rewrite, and the new system launches missing features the old one had.
Instead, we use the strangler fig pattern: new features and modules are built with modern technology, a routing layer directs traffic to either the legacy or modern system, and over time the modern system handles more and more of the workload. The legacy system gradually shrinks until it can be decommissioned entirely.
This approach lets you see value immediately — the first modern component can be in production within weeks — while managing risk. If anything goes wrong with a modern component, the legacy system is still there as a fallback.
Testing Legacy Code You Did Not Write
The scariest part of modifying legacy code is not knowing what will break. The system has no tests, the original developers are gone, and the business logic is encoded in thousands of lines of untested code. Before we change anything, we build a safety net.
We write characterization tests — automated tests that capture the current behavior of the system, even if that behavior is technically buggy. These tests do not validate correctness; they validate consistency. If our changes cause a test to fail, we know we have changed existing behavior and can evaluate whether that change is intentional.
For web applications, we use end-to-end tests with Playwright that exercise the critical user flows. For APIs, we record real request/response pairs and replay them against the modified system. This testing infrastructure becomes the foundation for safe, confident modernization.
Common Modernization Paths
PHP to Node.js/TypeScript: We have migrated several PHP applications (Laravel, CodeIgniter, WordPress custom plugins) to Node.js backends with React frontends. The key is mapping PHP session management, authentication, and database access to their modern equivalents while maintaining data compatibility.
jQuery to React: For applications with complex client-side logic built on jQuery, we introduce React incrementally — mounting React components within the existing page and gradually expanding until the jQuery dependency can be removed entirely.
On-premise to Cloud: Legacy applications running on physical servers or Windows Server VMs can be containerized and moved to cloud infrastructure. We handle the networking changes, database migration, and deployment pipeline setup required to make this transition safe. The most valuable part of a legacy system is not the code — it is the business logic the code implements. We document business rules as we encounter them, validate them with domain experts on your team, and implement them in the modern system with explicit test coverage.
Technologies We Use
Frequently Asked Questions
How long does legacy modernization take?
Will there be downtime during the migration?
Can you work with our legacy technology?
Should we rewrite or refactor?
Legacy System Holding You Back?
Get a free legacy system assessment. We will evaluate your current technology, identify modernization priorities, and map out a safe migration path.