Aging applications get slower, costlier and riskier every year — and a full rewrite feels too dangerous to start. Billow's application modernization services bring legacy applications forward through replatforming, refactoring and cloud-native rebuilds, cutting technical debt without betting the business on a big-bang rewrite.
Application modernization is the process of updating legacy applications — their code, architecture, platform and data — so they run reliably on modern, usually cloud-based infrastructure. Rather than replacing a working system outright, modernization brings aging software forward through rehosting, replatforming, refactoring or rebuilding — reducing technical debt, cost and risk while keeping the business logic that still earns its place.
Legacy applications rarely fail all at once. They just get harder — slower to change, more expensive to run, tied to old servers and skills that are disappearing, and increasingly a security and compliance liability. The instinct is to rewrite everything, but a big-bang rewrite is exactly where modernization projects go to die: too big, too risky, too long before anyone sees value. The better path is deliberate — modernize legacy applications incrementally, in the right order, using the right approach for each one.
Billow assesses your application portfolio, picks the right modernization approach for each system — rehost, replatform, refactor or rebuild — and modernizes to the cloud in increments that keep the business running. Our legacy modernization work often pairs with application migration to the cloud: whether it's moving a monolith to microservices, replatforming onto containers, or a full cloud-native rebuild, the goal is the same: less legacy drag, lower cost, and software that can keep up with the business again. It's app modernization done as a controlled program, not a leap of faith.
Our application modernization services cover the whole journey — deciding what to modernize and how, then replatforming, refactoring or rebuilding each application with minimal disruption.
We inventory your application portfolio, score each system on business value, risk and technical debt, and set the right approach and sequence for modernization.
Move legacy applications to the cloud — rehosting or replatforming onto containers and managed services — to cut cost and infrastructure risk fast.
Restructure aging code and break monoliths into microservices — improving scalability, maintainability and deployment speed without losing business logic.
When an application is past saving, we rebuild it cloud-native — modern stack, APIs and architecture designed for the way you work now.
Migrate data and integrations off legacy platforms safely — with validation and cutover planning that protects the business through the move.
Ongoing modernization delivered in increments, with support that keeps applications healthy and continues retiring technical debt over time.
Old applications quietly drain budget, block new features and pile up security and compliance risk. Application modernization stops the bleed — turning legacy drag into software that's cheaper to run and ready to change.
Retire aging servers, expensive licenses and specialist upkeep — modern, cloud-based applications cost less to operate and scale.
Refactored, well-architected applications ship features in days, not quarters — so technology stops being the bottleneck.
Modernizing off unsupported platforms cuts security, compliance and key-person risk — and pays down the technical debt behind it.
Cloud-native architecture and microservices give applications the elasticity and resilience legacy systems were never built for.
Every legacy application is different, so we match the approach to the system — from a quick lift to a full rebuild. Most portfolios use a mix.
Lift-and-shift → optimize
Move legacy applications to the cloud with minimal change, then replatform onto containers and managed services for quick, low-risk wins.
Monolith → microservices
Restructure the code and architecture — decomposing monoliths into microservices — for scalability, speed and maintainability.
Cloud-native or product
When legacy is past its limit, rebuild it cloud-native or replace it with a modern product — a clean break from the old constraints.
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We inventory the portfolio, map dependencies and technical debt, and score each application to choose the right approach and order.
We build an incremental modernization roadmap — quick wins first, big rewrites de-risked — with clear cost, value and cutover plans.
We replatform, refactor or rebuild in increments — using patterns like the strangler fig so the business keeps running throughout.
We tune cost, performance and reliability on the modernized applications, and keep retiring the remaining legacy over time.
Application modernization is the process of updating legacy applications — their code, architecture, platform and data — so they run reliably on modern, usually cloud-based infrastructure. Rather than replacing a system outright, modernization brings aging software forward through rehosting, replatforming, refactoring or rebuilding, reducing technical debt, cost and risk while keeping the business logic that still works.
The common approaches are often described as the Rs: rehost (lift-and-shift to the cloud with minimal change), replatform (move with targeted optimizations), refactor or re-architect (restructure the code, often monolith to microservices), and rebuild or replace (build new or adopt a modern product). Most real modernization programs mix these across an application portfolio based on business value and risk.
Replatforming moves an application to a modern platform — for example, onto containers or a managed cloud database — with limited code changes, to gain cloud benefits quickly. Refactoring goes deeper: it restructures the application's code and architecture, such as breaking a monolith into microservices, to improve scalability and maintainability. Replatforming is faster and lower-risk; refactoring delivers more but takes more effort.
We modernize incrementally rather than all at once. Using patterns like the strangler fig — standing up new, modern components alongside the legacy system and shifting functionality over piece by piece — we keep the application running throughout and reduce the risk of a single large cutover. Each increment delivers value and can be validated before moving on.
Yes. Cloud is where most modernization leads — whether that's rehosting to Azure or AWS, replatforming onto containers and managed services, or rebuilding as cloud-native applications. We assess each application, choose the right approach, and modernize it to the cloud in a way that improves cost, scalability and resilience without disrupting the business.
Modernization rarely stands alone. These related application services extend and complete it.
The full practice this sits within — application modernization, custom development and API & integration.
When modernization means a rebuild, we build the new application custom — designed around how you actually work.
Modernized applications need to connect — we build the APIs and integrations that tie them into the rest of your systems.
Point us at the application that costs the most and changes the least, and we'll show you a modernization path — the right approach, in the right order, with the business running the whole way.
