Web Application Modernization
Modernise legacy web applications with StepTo, monolith-to-microservices migration, framework upgrades, cloud migration, and API-first refactoring.
Reviewed by Igor Gazivoda, Co-founder & CEO of StepTo · Updated
StepTo revitalises legacy web applications, restoring speed, security, and the ability to ship, without throwing away the years of business logic already proven in your system. Our nearshore engineering teams in Belgrade, Serbia work in your timezone (CET) and deliver modernization at 40-60% below typical Western European and US agency rates. We favour incremental, zero-downtime change over risky big-bang rewrites, so the business keeps running while the codebase gets dramatically better. See our e-commerce platform rebuild case study for a real example, cutting load times 94% and lifting conversions 31% for a Dutch retailer.
What Modernization Services Do We Offer?
StepTo offers five web application modernization services: incremental refactoring, monolith-to-microservices decomposition, framework and stack upgrades, cloud migration and cost optimization, and test automation with CI/CD.
- Incremental refactoring, strangler-fig migration that replaces the old system feature by feature, with no overnight cutover.
- Monolith to microservices, careful service decomposition where it earns its keep, not architecture for fashion's sake.
- Framework & stack upgrades, migrating AngularJS, jQuery, legacy .NET, Java, and PHP to modern React/Next.js, Angular, and well-structured back ends.
- Cloud migration & cost optimization, moving workloads to AWS, Azure, or GCP and tuning them for performance and spend.
- Test automation & CI/CD, adding the safety net and delivery pipeline that make fast, confident releases possible.
How Does a Modernization Project Run?
A StepTo modernization project runs in four phases: discovery and assessment, a test safety net around existing behaviour, phased delivery behind feature flags, then cutover and decommission of the legacy components.
- Discovery & assessment, we map the codebase, dependencies, data model, and the business-critical paths, then propose the smallest high-impact plan.
- Safety net first, automated tests around existing behaviour before we change a line, so refactoring never silently breaks production.
- Phased delivery, feature flags and parallel runs route traffic gradually to the new code, keeping users live throughout.
- Cutover & decommission, retire legacy components only once their replacements are proven, with rollback paths at every step.
Why Choose StepTo?
StepTo is a Belgrade-based nearshore partner whose engineers work on complex monoliths and obsolete stacks rather than only greenfield builds, in CET hours, with a zero-downtime delivery approach.
- Engineers experienced with complex monoliths and obsolete stacks, not just greenfield builds.
- Zero-downtime approach, phased rollouts, feature flags, and safe data migrations.
- CET-timezone collaboration for real-time decisions during high-stakes migrations.
- 40-60% cost savings versus Western European and US agencies at equivalent seniority.
- Future-ready architecture your team can hire for and maintain.
What Do Teams Weigh Before Modernizing a Legacy App?
Teams typically weigh six questions before modernizing a legacy app: rewrite versus incremental refactor, downtime risk, which legacy stacks are covered, how project risk is reduced, the outcomes to expect, and cost.
- Should I rewrite my legacy app or refactor it incrementally?
- In most cases, incremental refactoring beats a full rewrite. Big-bang rewrites are notorious for running over budget and shipping late while the business waits. We typically apply the strangler-fig pattern: stand up the new architecture alongside the old system, route traffic feature-by-feature, and retire the legacy code only once its replacement is proven in production. A full rewrite makes sense only when the existing stack is genuinely unmaintainable or the technology is end-of-life, and even then we sequence it to keep the product live throughout.
- Will users experience downtime during modernization?
- No, keeping the product live is a core part of how we work. We use phased rollouts, feature flags, parallel-run validation, and database migration strategies (expand/contract) that avoid breaking changes. Most modernizations ship continuously, so users see steady improvements rather than a risky overnight cutover. When a hard cutover is unavoidable, we plan it with rollback paths and run it in a low-traffic window.
- Which legacy stacks can you modernize?
- We handle a wide range, older .NET Framework, Java/J2EE monoliths, PHP (including legacy Laravel and bespoke frameworks), AngularJS and jQuery front-ends, and even rarer or end-of-life stacks. The target is usually a modern, maintainable architecture: React/Next.js or Angular on the front end, a well-structured service layer, and cloud-native infrastructure. We assess the existing codebase first and recommend the smallest set of changes that delivers the outcome you need.
- How do you reduce risk on a modernization project?
- We start with a discovery and assessment phase that maps the codebase, dependencies, data model, and the real business-critical paths. From there we sequence work to deliver value early and de-risk the hardest parts first. Comprehensive automated tests are added around legacy behaviour before we change it, so we can refactor with confidence and catch regressions immediately.
- What outcomes can I expect from modernizing?
- Typical results include faster page loads and better Core Web Vitals, lower infrastructure and maintenance costs, the ability to ship features in days instead of months, improved security posture, and a codebase your team can actually hire for. Modernization is not refactoring for its own sake. It is about restoring the speed and agility a maturing product loses to accumulated technical debt.
- How much does web application modernization cost?
- It depends on the size and condition of the existing system, but because our engineers are based in Serbia, you get senior modernization specialists at 40-60% below comparable Western European and US agency rates. Most clients engage a dedicated team from $15K-25K/month for three engineers and work in continuous sprints, so cost scales with scope and you control the pace. We can scope a fixed first phase after the discovery assessment.