Senior Java Developer

N-iX is looking for a Senior Java Developer to join a long-term modernization initiative for a large US-based provider of marketing, packaging, print, and supply chain services serving Fortune-level clients worldwide.

You will work within the customer's European supply chain division, supporting warehousing, fulfillment, kitting, and packaging operations for global brands in electronics, medical devices, and consumer products. The main stakeholder is a Software Development Manager who originally built the system and remains deeply involved in its technical evolution.

About the Project

The project focuses on a customer-facing web portal that has been operating successfully for over two decades. The portal enables customers, suppliers, and partners to:

View inventory, goods, and shipment reports

Exchange files securely

Submit forecasts and operational data

Access supply chain information

The system has been in maintenance mode for several years and now requires a strategic technology uplift to address security vulnerabilities and ensure continued support for the next 5–7 years. This is not a rewrite project. The goal is a cost-effective modernization of the existing platform while preserving business-critical functionality.

Technology Stack

Java 8

Struts 1.1

STXX (XML/XSLT)

Apache Tomcat 9

Apache HTTP Server

Linux

Ant

Azure DevOps

Data & Integrations:

Microsoft SQL Server

Oracle Database

Stored Procedures

LDAP

SFTP

Email integrations

Application Size:

200,000+ lines of Java code

Monolithic architecture

No automated test coverage currently in place

Responsibilities

Lead and execute the migration of a large legacy Java application

Upgrade Java versions and modernize the framework stack

Perform migration from javax to jakarta

Upgrade dependencies and address security vulnerabilities

Analyze and refactor legacy code where required

Create unit and integration tests for existing functionality

Support regression testing activities

Collaborate closely with the customer’s technical stakeholders

Deliver early security improvements and test coverage for critical business flows during the initial project phase

Requirements

Must Have

5+ years of commercial experience with Java

Proven experience working with Struts 1.x

Experience with Java version upgrades and/or framework migration projects

Strong knowledge of Apache Tomcat and Linux environments

Experience working with SQL Server and Oracle databases

Solid understanding of JDBC and stored procedures

Experience testing and maintaining legacy applications

Strong problem-solving and debugging skills

Fluent spoken and written English

Based in the EU

Nice to Have

Experience with AI-assisted migration tools (OpenRewrite, GitHub Copilot, Claude, Gemini, etc.)

Knowledge of XSLT/XML transformations

Experience migrating build systems from Ant to Maven or Gradle

Experience with Azure DevOps

Experience with large monolithic enterprise applications