Senior Java Software Engineer

• 5+ years of backend Java development
• Strong Core Java skills - comfortable without Spring Boot
• Experience with concurrency and multithreading
• Familiar with JUnit, Mockito, or similar testing frameworks
• Experience with relational or NoSQL databases (PostgreSQL, Oracle, MySQL, SQL Server, MongoDB)

Bonus if you have experience in one of these areas:

• Networking: Netty, Java NIO, sockets, TCP/IP, HTTP/HTTPS, gRPC, Vert.x
• Distributed systems: Kafka, AMQP, MQTT, REST, WebSocket
• Platform engineering: high availability, load balancing, connection pooling, failover, performance optimization
• AI-focused engineering

• Up to 95K annually
• Fully remote within the Netherlands
• Etc. :-

Are you a core Java developer who knows their way around complex, high-performance codebases without leaning on Spring Boot? And do you like the idea of working on a platform that connects business systems for over 2,000 customers worldwide?

Keywords: Java 21, Core Java, Netty, Jetty, JPA, PostgreSQL, Concurrency, Multithreading, Monolith

My client builds a data integration platform that powers supply chains through real-time integration, automation, and intelligent data processing. Think connecting cloud and on-premise systems at scale, for thousands of customers globally.

The codebase is a Java 21 monolith. No microservices, no Spring Boot. Instead, the team has built homegrown frameworks on top of Netty, Jetty, and JPA. If you’re someone who actually understands what’s happening under the hood, you’ll feel right at home here.

You’ll be designing, building, and maintaining production-grade backend software, contributing to technical design and code reviews, and taking full ownership of features from implementation through to production.