Development
Java and Spring Boot development
Java is the reference language for enterprise information systems: banking, insurance, manufacturing, logistics, public sector. Spring Boot is the framework that modernized its ecosystem by simplifying configuration, API exposure, data access, security and container deployment.
Agencei develops with Java and Spring Boot for organizations that need robust backends, microservices, enterprise APIs or batch processing, and for those that must modernize legacy Java applications (Java EE, Struts, outdated Spring versions) without interrupting operations.
We work on complete projects or as reinforcement for your in-house teams, applying proven engineering practices: automated tests, continuous integration, observability, code reviews and documentation that outlives the project.
When do we step in?
Building an enterprise backend
Your system must handle complex business rules, reliable transactions and large volumes, with traceability requirements. Spring Boot and a relational database form a proven foundation.
Splitting an application into microservices
A monolithic Java application is slowing your deployments. We identify domains, extract autonomous Spring Boot services and organize their communication.
Modernizing a legacy Java application
Java 8 or earlier, heavy application server, abandoned frameworks: we migrate to recent Java and Spring Boot versions in verifiable steps.
Automating batch processing
End-of-day calculations, large file imports, report generation: Spring Batch structures these jobs with error recovery and monitoring.
Reinforcing a Java team
You need experienced Spring Boot developers to meet a deadline, absorb a workload or pass on good practices to your team.
How we work
- 1
Assessment of the existing system or scoping
Review of architecture, versions, dependencies and weak points for an existing system; definition of domains and flows for a new project.
- 2
Architecture and technical choices
Breakdown into modules or services, data model, security (Spring Security, OAuth 2.0), asynchronous messaging, deployment strategy.
- 3
Development with tests
Iterative development with unit tests, integration tests on a real database via Testcontainers and systematic code reviews.
- 4
Continuous integration and containerization
Build and test pipelines, optimized Docker images, deployment on Kubernetes or on your infrastructure.
- 5
Observability and performance
Metrics, structured logs, distributed tracing, load testing and tuning of the JVM and data access.
- 6
Production rollout and handover
Gradual cutover, operations documentation, knowledge transfer and support for your teams.
Technologies we use
- Java 17 and 21
- Spring Boot
- Spring Security
- Spring Data JPA
- Spring Batch
- Hibernate
- PostgreSQL
- Kafka or RabbitMQ
- Maven or Gradle
- Testcontainers
- Docker
- Kubernetes
Why choose Agencei?
Modern Java, not Java from fifteen years ago
Recent language versions, up-to-date Spring Boot, fast startup, lightweight containers: we apply the ecosystem's current practices.
Migrations without a big bang
We modernize Java applications in verifiable steps, with tests that freeze existing behaviour before each change.
Solid fundamentals
Transactions, concurrency, memory management, data access: we master the topics that make the difference as volumes grow.
Compatible with your enterprise constraints
We know how to work with approval processes, audit requirements and internal operations teams.
In brief
- What is this service?
- Development, modernization and maintenance service for enterprise applications, microservices, APIs and batch processing with Java and Spring Boot.
- Who is it for?
- Organizations that need robust, traceable backends, or that run legacy Java applications to be modernized without interrupting operations.
- What problem does it solve?
- Having a reliable, high-performance and maintainable Java foundation, and moving away from obsolete versions that hinder evolution and expose you to vulnerabilities.
- How long does it usually take?
- From a few weeks for a focused service or API to several months for a complete enterprise application or a staged migration of a legacy system.
- What factors influence the price?
- Complexity of business rules and transactions, number of services and integrations, condition of the existing code to modernize, security, audit and performance requirements.
- How does the engagement run?
- Assessment or scoping, architecture, development with automated tests, continuous integration and containerization, observability and load testing, production rollout and handover.
- What are the risks?
- Big-bang migration that breaks undocumented behaviour, premature microservice breakdown, obsolete dependencies, performance not tested under real load.
- What alternatives exist?
- Node.js or Python for lightweight services if your team masters them, Kotlin on the JVM for a more concise syntax, or keeping the current system with patches if modernization is not justified.
Frequently asked questions
Is Spring Boot still a good choice today?
Yes. Spring Boot remains the most widely used framework in the Java ecosystem, actively maintained, with long-term support releases, native container integration and extensive documentation. It is a safe choice for systems that must last.
Which Java version do you use?
We favour the most recent long-term support versions, currently Java 17 and Java 21, which bring performance and readability gains. For migrations, we start from your current version and progress in stages.
Should we move to microservices?
Not systematically. A well-structured modular monolith suits many organizations. Microservices are justified when several teams need to deploy independently or when parts of the system have very different scaling needs.
Can you take over a Java application without documentation?
Yes. We start by mapping the code and dependencies, add characterization tests that freeze current behaviour, then work safely on the areas to change.
How do you guarantee performance?
Through representative load tests, SQL query analysis, caching where relevant, JVM tuning and production monitoring that detects drift before users do.
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See this serviceTell us about your project
Describe your need in a few lines: we come back to you with a first analysis and the next steps.