Top Java application migration companies (+ what to look for before you hire)

Your 15-year-old Java system still processes millions in revenue. It also breaks every time someone touches the checkout module. The test suite covers maybe 12% of the codebase. Three engineers who understood the domain logic left two years ago. And now leadership wants it “cloud-ready” and “AI-ready” by Q3.

You’ve heard the pitch: rip it out, rebuild from scratch, 18 months, $4M. That pitch ignores what actually happens with brownfield systems, undocumented business rules, and stretched teams.

Java application migration done well starts with figuring out what to keep, refactor, and retire — then moves in small, reversible steps that prove value in weeks.

This article evaluates java application migration companies based on how they actually work.

What you’ll find here:

• A curated list of Java app migration companies for complex, brownfield systems
• Evaluation criteria: diagnostic depth, risk management, and AI-readiness capability
• Red flags when vetting java migration companies
• What a real Java modernization diagnostic should include
• Migration patterns that reduce risk during and after the move

What makes a java migration company worth hiring

Most vendor evaluation starts with “how many Java developers do they have?” That’s the wrong question. Headcount doesn’t tell you whether a company can analyze your 800,000-line Java EE monolith and identify which 200,000 lines actually matter.

Ask these questions instead:

• Do they start with a diagnostic? A credible java migration company insists on understanding your system before proposing architecture changes. If the first deliverable is a 6-month rebuild proposal based on two calls, walk away.
• Can they distinguish between keep, refactor, and retire? Most vendors default to greenfield because it’s easier to sell and staff. But CTOs with revenue-critical systems need selective modernization. Ask for examples where they left parts of a monolith in place.
• Do they embed with your team? If your engineers can’t own the result after engagement ends, you’ve bought a dependency. Look for knowledge transfer in the SOW.
• Do they know modernization patterns beyond “microservices”? Strangler-fig, modular decomposition, in-place re-platforming. If their pitch deck only mentions microservices, they may lack depth.
• Is their AI-readiness story specific? Exposing domain services as APIs, cleaning data contracts, introducing event streams — these are concrete steps. If AI is just a slide, it’s a buzzword.
• Do case studies show partial modernization? Full rewrites make flashy case studies. Partial modernization — keeping 60% and rebuilding 40% — is often the right call.

Evaluation checklist

Top java application migration companies

1. Techstack

Every Techstack engagement opens with a 2-to-3-week assessment before any code changes. That assessment maps architecture, dependencies, data flows, and integration points, identifies modules with high defect rates and change frequency, surfaces dead code, and produces a written keep/refactor/rebuild/retire matrix scored by business value, technical risk, and change frequency. You get a written scope, risk register, and cost estimate before committing to development — applied to every project regardless of size.

The team on every project includes Java architects with enterprise system design experience and senior Java developers who specialize in the stack. Their delivery record spans sales enablement, logistics, fintech, and healthcare: version migrations, cloud migrations, monolith decompositions, and analytics rebuilds, all in production environments.

The reference engagement is a 5+ year project with a California-based sales enablement company: a Java monolith broken into modular microservices, an analytics subsystem rebuilt using CQRS and Amazon Redshift, operational costs reduced by up to 3x, with 40+ engineers across multiple Scrum teams and no interruption to the live platform. The case study describes the approach in detail.

Limitation: Not a fit for portfolio-level migrations across 20+ applications or enterprises needing 150+ developers on a single engagement.

Best for: US and EU mid-market companies wanting engineering-focused partners for incremental Java modernization with AI components.

2. Broadcom / VMware Tanzu (now part of Broadcom)

VMware Tanzu Labs built its reputation on Spring Boot and Spring Cloud. They know the Spring ecosystem deeply — they created much of it. For organizations running Spring-based Java applications, Tanzu offers migration paths to Kubernetes via Tanzu Application Platform, including containerization, CI/CD setup, and app-level refactoring.

Engagements include modernization assessment followed by iterative app-level migrations, often pairing client developers with their engineers. Strength: if your stack is Spring and your target is Kubernetes on VMware, few vendors have more direct product-to-service alignment.

Limitation: Broadcom’s acquisition introduced pricing and licensing changes that concern some customers. If your system runs Java EE on WebSphere or JBoss rather than Spring, the fit weakens. Tanzu assumes a Spring-centric world.

Best for: Spring-based Java shops already invested in VMware infrastructure targeting Kubernetes migration.

3. Red Hat Consulting

Red Hat specializes in moving legacy Java EE workloads (especially JBoss EAP) to cloud-native stacks using Quarkus, OpenShift, and Red Hat Runtimes. Their Migration Toolkit for Applications (MTA) automates parts of analysis, flagging APIs, dependencies, and code patterns needing changes.

Red Hat Consulting follows a phased model: assess, pilot, scale. Strong on infrastructure-level modernization — containers, OpenShift deployment, CI/CD on Tekton. Quarkus offers faster startup times and lower memory usage than traditional Java EE, important for Kubernetes.

Limitation: Engagements orient toward the Red Hat/OpenShift ecosystem. If you want cloud-agnostic results or target AWS ECS/Fargate or Azure Container Apps, expect friction. Assessment phases tend to be longer and less time-boxed than 2-week sprints.

Best for: Java EE / JBoss shops wanting to stay within Red Hat/OpenShift ecosystem and move to Quarkus or modernized JBoss EAP.

4. EPAM Systems

EPAM handles large-scale migrations from legacy Java EE and proprietary middleware to Spring Boot, cloud-native containers, and managed cloud services. Teams include architects experienced with WebLogic, WebSphere, and Struts-era codebases.

What distinguishes EPAM: their engineering culture. Engagements staff with senior engineers who read legacy code and make architecture-level decisions rather than follow runbooks. EPAM’s growing data engineering and AI/ML practice connects modernization to downstream AI initiatives concretely.

Tradeoff: large company. Engagement sizes tend to be substantial. Smaller projects (under $500K) may not get their A-team. Expect longer sales cycles and more overhead than boutique companies.

Best for: Mid-to-large enterprises with complex Java estates needing engineering depth and capable of supporting larger engagements.

5. Infosys

Infosys runs large-scale Java EE to cloud-native migrations for Fortune 500 companies, covering re-platforming, refactoring, and re-hosting. They’ve built proprietary automation for code analysis, dependency mapping, and automated testing during migration.

The GSI model enables scale: staffing 50-person teams across time zones. For $100M-revenue enterprises with 30 Java applications, Infosys runs parallel workstreams smaller companies can’t.

Constraint: engagements run 12–24 months with significant discovery before production migration. Teams mix senior architects with junior developers, so quality varies. If your goal is modernizing one critical system fast with 8–12 week proof-of-value, their process may feel heavy.

Best for: Large enterprises with multiple Java applications needing portfolio-level coordination across business units.

6. Perficient

Perficient is a US-based digital consultancy with a mid-market Java modernization practice. They work with Spring Boot, cloud-native patterns on AWS and Azure, and migrate applications off proprietary middleware. US-based delivery matters for data residency requirements or same-timezone preference.

Caveat: Perficient is a generalist consultancy; Java migration is one practice. Expertise depth varies by assigned team. Meet your architects before signing.

Best for: US mid-market companies wanting domestic delivery and defined-scope Java migration.

7. Ness Digital Engineering

Ness focuses on engineering-led modernization for mid-market and enterprise clients, with experience in Java migration and cloud-native builds. They’ve executed Java-to-Spring Boot refactoring, monolith decomposition, and containerized deployment on AWS and Azure.

Ness typically takes incremental approaches aligned with strangler-fig patterns. Teams identify bounded contexts in existing monoliths and extract services one at a time. Their data engineering practice helps when migration requires database modernization (Oracle to PostgreSQL) alongside application changes.

Smaller than EPAM or Infosys means more consistent senior staffing.

Limitation: Capacity constraints apply to very large migrations (10+ applications, 100+ developers). No published diagnostic or assessment methodology comparable to structured 2-to-3-week engagement models — scope definition process is less transparent upfront.

Best for: Companies with multi-system Java estates where application modernization and data platform work need to run in parallel.

Red flags when evaluating java app migration companies

They skip the diagnostic. Any company proposing a 6-month architecture after two calls hasn’t looked at your code. A legitimate java application migration company needs to see the system before making promises.

Their case studies are all full rewrites. If every success story starts with “we rebuilt from scratch,” they may not know selective modernization. Selective modernization is harder.

No observability plan. If they don’t discuss instrumenting with tracing, metrics, and logging before migration, they’re planning blind. You’ll learn about regressions from customers, not dashboards.

Lock-in risk in the proposal. A proprietary PaaS, single-vendor toolchain with no exit path, or custom framework only they understand. Ask: “If we end this engagement tomorrow, can our team run and change what you’ve built?”

Knowledge transfer missing from the SOW. Without pairing sessions, documentation, and handoff milestones, your team can’t maintain the result. You’ll call the same vendor for every change.

More buzzwords than patterns. If they say “digital transformation” repeatedly but can’t name specific migration patterns (strangler-fig, branch by abstraction, parallel run), they’re selling strategy, not engineering.

What a java application migration diagnostic should include

“How do we estimate cost and timeline for modernizing a 15-year-old Java system?” You can’t do it accurately until someone examines the code, dependencies, and data.

This diagnostic doesn’t lock you into a multi-year engagement. It gives you a document your team and board use to make informed decisions.

Java migration patterns that reduce risk

Strangler fig. Route new functionality through new services while the legacy system stays live. Over time, traffic shifts to new components. The old code shrinks until you can turn it off. Safest path for revenue-critical systems.

Modular monolith as an intermediate state. Not everything needs microservices. Refactoring the monolith into well-bounded modules with clean interfaces delivers most maintainability benefits at a fraction of operational complexity.

Observability-first migration. Instrument with OpenTelemetry before migrating. Understand traffic patterns, latency baselines, and error rates in the current system. Without this baseline, you won’t know if the migrated version is better.

Feature toggles. Decouple deployment from release. Ship new code behind a toggle, route a percentage of traffic, and roll back without downtime if needed. Migration becomes a series of small, reversible steps rather than big-bang events.

Bounded context identification. Map domain logic before decomposing. Talk to the business. Understand real boundaries. Skipping this creates distributed monoliths — the worst of both worlds.

Final thoughts

Java systems built in 2008 still run critical business in 2025. The question isn’t whether to modernize — it’s how to do it without betting the business on a multi-year rebuild. Run the diagnostic first. Know what you actually have. Move in small steps that prove value fast.

→ Talk to Techstack about your Java system

Frequently asked questions

How do we break up a Java EE monolith without a full rewrite?

Identify bounded contexts in domain logic. Use strangler-fig to extract one context at a time into a standalone service. Keep the monolith running for everything else. This reduces risk and delivers incremental results.

What’s the safest way to migrate from WebLogic or WebSphere to cloud-native?

Instrument the existing system first with tracing and metrics. Migrate one workload at a time to Spring Boot or Quarkus on containers. Run old and new versions in parallel until behavior and performance validate. Avoid big-bang cutovers.

How do we identify which codebase parts are still used before removing them?

Combine static analysis (dependency graphs, dead code detection) with runtime analysis (which endpoints receive traffic, which modules are invoked in production). A 2-week diagnostic produces both.

Can we modernize our Java app in place and still make it AI-ready?

Yes. AI-readiness comes from exposing domain capabilities as APIs and cleaning data contracts. You don’t need a new system. You need well-defined service boundaries and accessible data. Spring AI and LangChain4j plug into existing systems once APIs and event streams are in place.

How long does a java application migration typically take?

It depends entirely on the system. A single monolith with well-understood domain logic might take 3–6 months to partially modernize. A portfolio of 10+ interconnected Java applications could take 12–24 months. Start with a time-boxed diagnostic that gives realistic timelines based on actual code analysis.

What should we look for when selecting java migration services?

Look for java migration services that start with a structured diagnostic, understand your specific business constraints, and follow proven patterns like strangler-fig decomposition rather than big-bang rewrites. Ensure the java migration services provider embeds with your team for knowledge transfer and can demonstrate experience with your specific technology stack.

What’s the difference between re-platforming and modernization?

Re-platforming (lift-and-shift) moves your application to new infrastructure without code changes. Modernization changes the application itself: refactoring architecture, updating frameworks, decomposing modules, and exposing APIs. Re-platforming is faster but delivers fewer long-term benefits. Modernization addresses root causes of technical debt.