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Java
PostgreSQL
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AWSWhy Java
Java has powered enterprise software for decades, and modern Java is very different from the verbose language many remember. Records, pattern matching, virtual threads and frequent long-term-support releases make it productive and performant, while its mature ecosystem, tooling and talent pool make it a safe choice for systems expected to run for many years.
Many banks, insurers, logistics companies and governments run critical systems on Java. We build new Java services and help modernise existing ones.
When Java is the right choice
| Details | |
|---|---|
| Great fit | Large enterprise systems, financial services, high-throughput back ends, organisations with existing Java expertise |
| Consider alternatives | Small web apps or startups optimising for speed of first release |
What we build with Java
Enterprise applications
Business systems with complex rules and integrations.
APIs & microservices
Spring Boot services with clear contracts.
Integration services
Connecting ERPs, mainframes and modern apps.
Modernization
Java EE, old Spring and monoliths moved to modern Java.
Our Java toolkit
Modernising legacy Java
Older Java systems — Java 8 or earlier, application servers such as WebLogic or JBoss, Java EE — can be modernised step by step: upgrading to a current LTS release, replacing application servers with embedded Spring Boot, containerising, adding automated tests and extracting services where it helps. Each step brings security fixes and performance gains, and reduces hosting and licensing costs.
Modern Java is not the Java you remember
Java has changed significantly in recent releases. Records remove boilerplate from data classes, pattern matching and switch expressions make code more concise, text blocks simplify embedded SQL and JSON, and virtual threads (production-ready since Java 21) allow simple blocking code to handle very high concurrency without complex reactive frameworks. Long-term support releases arrive every two years, giving enterprises a predictable upgrade path.
Upgrading legacy Java applications
Many organisations still run critical systems on Java 8 or 11, often on outdated application servers. Upgrading reduces security risk and hosting cost and unlocks modern tooling.
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Assess1–2 weeks
Inventory dependencies, frameworks, application servers and test coverage.
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Prepare
Add characterisation tests around critical behaviour and set up CI with the target JDK.
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Upgrade in steps
Move through LTS versions, updating libraries such as Spring and Hibernate; tools like OpenRewrite automate many changes.
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Modernise deployment
Package as containers and move from heavyweight app servers to embedded runtimes where practical.
JVM ecosystem choices
- Spring Boot — the default for enterprise services, with the largest ecosystem.
- Quarkus and Micronaut — faster start-up and lower memory, attractive for containers and serverless.
- Kotlin — fully interoperable with Java, more concise, and a strong option for new services.
- GraalVM native images — near-instant start-up for specific workloads, with some trade-offs in build time and reflection support.
When to choose Java for a new project
Java is a strong choice when an organisation already has Java expertise and infrastructure, when the system must integrate with enterprise platforms that offer first-class Java SDKs, or when long-term stability and backward compatibility matter more than speed of initial development. Its mature tooling for profiling, monitoring and debugging is a real advantage for high-volume transactional systems in banking, insurance, telecoms and logistics. For a small startup building an MVP, frameworks such as Laravel, Django or Next.js may reach market faster — but Java scales with the organisation as teams and traffic grow, and the hiring pool for experienced Java engineers remains one of the largest in software.
Choosing a Java LTS version
Java now ships a new feature release every six months, with a long-term support (LTS) release every two years. Most organisations build on LTS releases. Each LTS adds substantial improvements: records, pattern matching, text blocks and sealed classes make code shorter, while virtual threads (Java 21) make high-concurrency servers far simpler to write.
| Current version | What we usually recommend |
|---|---|
| Java 8 | Plan a staged upgrade to a current LTS — many libraries and frameworks no longer support it |
| Java 11 | Upgrade to Java 17 or 21; changes are usually modest |
| Java 17 | Supported and stable; move to 21 to gain virtual threads when convenient |
| Java 21 or later LTS | Keep current with regular patch updates |
Support dates vary by JDK vendor (Oracle, Eclipse Temurin, Amazon Corretto, Microsoft Build of OpenJDK).
Testing and quality tooling
- JUnit 5 and AssertJ for readable unit tests
- Mockito used sparingly — we prefer testing real collaborators where practical
- Testcontainers for integration tests against real PostgreSQL, Kafka or Redis
- ArchUnit to enforce module boundaries and layering rules
- Static analysis with SpotBugs, Error Prone or SonarQube
- OWASP Dependency-Check or Snyk for vulnerable libraries
Performance and JVM tuning
Modern JVMs perform well out of the box, but production services benefit from deliberate choices.
| Area | What we look at |
|---|---|
| Garbage collection | G1 by default; ZGC for low-latency services with large heaps |
| Container awareness | Heap sized as a percentage of container memory, not hard-coded |
| Startup time | Class data sharing, or GraalVM native images for serverless and CLI tools |
| Concurrency | Virtual threads for blocking I/O-heavy workloads |
| Profiling | Java Flight Recorder and async-profiler in staging and production |
Deployment and operations
- Container images built with Jib or Buildpacks — no hand-written Dockerfiles needed
- Deployment to Kubernetes, AWS ECS, Azure Container Apps or application servers you already run
- Health checks, metrics and tracing through Micrometer and OpenTelemetry
- Database migrations versioned with Flyway or Liquibase
- Blue-green or rolling releases with automated rollback
- Centralised logging with correlation IDs across services
Most of our Java web work uses Spring Boot. For teams that need extra capacity, see hire Java developers.
What to check before taking on a legacy Java system
- Which Java version and application server does it run on, and who supports them?
- How is it built — Maven, Gradle, Ant or a manual process?
- Are there automated tests, and do they pass?
- Which frameworks are end-of-life (Struts 1, older Spring, Java EE on old servers)?
- Where is configuration stored, and how are secrets handled?
- Who knows how the deployment works, and is it documented?
Java beyond web applications
Java is not only for web back ends. Its maturity and tooling make it a strong choice for several other kinds of software we build and maintain:
Batch and data processing
Spring Batch jobs for imports, reconciliations and nightly processing with restart and audit support.
Event streaming
Kafka producers, consumers and Kafka Streams applications for real-time pipelines.
Integration services
Apache Camel or Spring Integration connecting ERP, CRM and legacy systems.
Search and analytics
Services built around Elasticsearch, OpenSearch or Apache Lucene.
Many organisations also run Java applications that predate Spring Boot — on WebLogic, WebSphere or JBoss. We can maintain them as they are, or move them gradually to lighter runtimes as part of a modernisation plan.
Questions we ask at the start of a Java engagement
- Which JDK distribution and support arrangement does the organisation use?
- Are there architectural standards, shared libraries or platform teams to align with?
- What are the integration points — databases, message brokers, mainframes or external APIs?
- How are releases approved and deployed today?
Work with us
Part of our backend technologies. See Spring Boot development and legacy modernization.
This page is part of Backend Development Services — see the full overview for related services, approach and pricing.