# Enterprise Java Modernization for Banks and Enterprises | DevsReady > DevsReady modernizes enterprise Java and legacy applications for banks, fintechs and enterprises: incremental migration with the strangler fig pattern, Java and Spring upgrades, monoliths split into services where justified, and evolutive maintenance. URL: https://devsready.io/application-modernization Last updated: 2026-10-18 Services ## Enterprise Java modernization DevsReady modernizes enterprise Java applications, and the legacy systems around them, for banks, fintechs and enterprises: incremental migration, Java and Spring upgrades, monoliths split into services where it pays off, and evolutive maintenance of live systems, using Java, Spring Boot, React, Docker and AWS. Updated October 18, 2026 ### Who enterprise Java modernization is for Engineering leaders whose systems can no longer keep up: a monolith that slows every release, a Java or Spring version out of support, a stack that limits scalability, or interfaces that fail accessibility expectations. Typical buyers are CTOs at banks, fintechs, enterprises and system integrators that cannot switch the old system off and need a partner that keeps it shipping while it changes. ### Typical use cases What DevsReady builds when an enterprise system has to change while it keeps running: - **From a .NET monolith to Java services on AWS :** Business logic moved to Java and Spring Boot microservices with a React frontend, deployed as containers on AWS. [Case study](https://devsready.io/case-studies#sports-betting-platform-technology-upgrade) - **Java and Spring Boot 3 upgrades :** Upgrades in tested steps, so the application stays deployable at every stage. - **Taking over a live platform :** Evolutive maintenance that keeps delivering new features and fixes while the system changes. [Case study](https://devsready.io/case-studies#retail-banking-platform) - **Accessibility refactoring :** Existing web interfaces refactored with WCAG-compliant components and keyboard and screen reader support. [Case study](https://devsready.io/case-studies#accessibility-compliance-digital-banking) ### Our approach: incremental migration with the strangler fig pattern DevsReady avoids big-bang rewrites. A routing layer goes in front of the legacy application, and capabilities move to new Java and Spring Boot code one at a time, each with its own release and a way back. Capabilities that change often or block the roadmap move first. Strangler fig migration - Clients - Web and mobile apps - Partner systems - Routing layer - API gateway or proxy - Instant switch back - Side by side - Legacy application, shrinking - New Java services, growing - Safety nets - Characterization tests - Contract tests - Parallel runs - Data - Shared database at first - Moved per service when justified Each capability moves behind the routing layer only when its safety nets pass. ### Testing safety nets before the first change - **Characterization tests :** Record what the system does today, quirks included, so a change in behavior is caught before release. - **Contract tests :** Check every API and message exchanged with other systems. - **Parallel runs :** Old and new code process the same input and their results are compared before traffic moves. - **No untested code :** Engineers own their code up to production monitoring, and untested code never ships. ### Java and Spring upgrades An upgrade to a current Java release and Spring Boot 3 is more than a version bump: javax packages move to Jakarta EE, unsupported dependencies are replaced and old framework behavior is removed. DevsReady upgrades in tested steps, so the application stays deployable at every stage. ### From monolith to services, when it is justified Microservices add network calls and operational cost, so they pay off only where parts of the system must scale, change or release independently. Otherwise a modular monolith on a modern stack is often the better answer, and DevsReady says so. When services are justified, boundaries follow business capabilities and each service owns its data. ### What we deliver in a modernization project - **Target architecture :** From service boundaries to deployment, designed to scale where the old system did not. - **Legacy migration and upgrades :** Business logic moved to Java and Spring Boot, frameworks brought to a modern stack, and containers on AWS or a platform you already use, such as OpenShift. - **Evolutive maintenance :** New features and fixes on the live system while it changes. - **Accessibility refactoring :** WCAG-compliant components with keyboard and screen reader support. ### How we de-risk your modernization - **Discovery first :** A conversation about goals, systems and constraints, under an NDA if you need one. - **Free proof of concept :** When you continue with DevsReady, from signed contract to working prototype in about one month, often one capability behind the routing layer. - **Contract terms in writing :** The engagement, including code and IP ownership, is agreed in writing before work begins. - **AI with human judgment :** An experienced engineer reviews and owns every decision that reaches production. ### Modernization technologies: legacy and target stacks DevsReady works with .NET and C# alongside Java, Spring Boot, Quarkus, React and Angular, and builds on Kafka, Elasticsearch, Oracle, Docker, Kubernetes, OpenShift and AWS. Accessibility work has covered React, HTML, CSS and jQuery interfaces. ### Proof: modernization case studies For one of the world's largest sports betting platforms, DevsReady replaced a monolithic .NET player monitoring system with Java and Spring Boot microservices and a React frontend, fully deployed on AWS with containerized services for better scalability, resilience and faster releases. The Retail Banking Platform and Accessibility Compliance for Digital Banking case studies show evolutive maintenance and interface refactoring on live banking systems. [Read the verified DevsReady reviews on Clutch](https://clutch.co/profile/devsready#reviews) ### Related case studies - [Sports Betting Platform - Technology Upgrade For one of the world's largest sports betting platforms, we contributed to the migration of their internal player monitoring system. Read the case study](https://devsready.io/case-studies#sports-betting-platform-technology-upgrade) - [Retail Banking Platform We provide evolutive maintenance for the web platform of one of Europe’s largest banks - the platform that powers the retail banking experience for the group’s banks across the CEE region. Read the case study](https://devsready.io/case-studies#retail-banking-platform) - [Accessibility Compliance for Digital Banking We supported a large European bank in making its digital applications fully accessible to users with disabilities, ensuring compliance with international accessibility standards. Read the case study](https://devsready.io/case-studies#accessibility-compliance-digital-banking) ### Frequently asked questions #### Can DevsReady work on a platform that must stay live during modernization? Yes. DevsReady already provides evolutive maintenance for the live retail banking platform of a large European banking group, shipping new features while keeping it stable, secure and compliant. #### Can DevsReady migrate a .NET application to Java and Spring Boot? Yes. For a global sports betting platform, the team replaced a monolithic .NET application with Java and Spring Boot microservices deployed on AWS. #### Does every modernization end with microservices? No. Microservices are worth their cost only where parts of the system must scale or release independently; otherwise a modular monolith on a modern stack is often better, and the choice is made with you in discovery. #### Can DevsReady take over an existing platform instead of rewriting it? Yes. Evolutive maintenance is part of modernization: DevsReady takes over a live platform and keeps delivering new features, enhancements and fixes. ### Questions buyers ask Direct answers on how an engagement starts, what drives the cost, contracts and support. Prices are quoted per project after a discovery call. #### How does a modernization project with DevsReady start? With a conversation about your systems, goals and constraints. A free proof of concept, from signed contract to working prototype in about one month, then validates the migration approach. #### How is a modernization project priced? Each one is quoted separately, because the cost depends on the size and condition of the legacy system, its existing tests, the target architecture, the engagement model and the duration. The proof of concept is free when you continue with DevsReady. #### Who supports the system after the migration? You choose. DevsReady hands the system over to your team or stays on for evolutive maintenance, with the scope of support, response times and hours of cover agreed in the contract. More answers on engagement models, cost, time zones, compliance and IP ownership in the [nearshore FAQ](https://devsready.io/faq). ### Planning a project like this? Tell us about your goals, your systems and your constraints. You will talk directly with the architect who would lead the work. [Book a discovery call](https://devsready.io/#contact)[contact@devsready.io](mailto:contact@devsready.io) BOUTIQUE SOFTWARE ENGINEERING - [Fintech software](https://devsready.io/fintech-software-development) - [Banking software](https://devsready.io/banking-software-development) - [Payments](https://devsready.io/payment-systems-integrations) - [Java modernization](https://devsready.io/application-modernization) - [Case studies](https://devsready.io/case-studies) - [FAQ](https://devsready.io/faq) - [Community](https://devsready.io/community) - [Careers](https://devsready.io/join-us) - [devsready.ro](https://devsready.ro/) Iuliu Maniu Boulevard 13D, Bucharest Romania [contact@devsready.io](mailto:contact@devsready.io) | [+40 735 891 972](tel:+40735891972) © 2026 DevsReady - All Rights Reserved.