Senior Full Stack Developer (Java 21, React, Kafka)
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Salary
$76k – $88k per year
Location
In office (Warsaw)
Seniority
Senior
Employment
Contractor
First seen by Alion on Oct 28, 2026.
Overview
Company
Impact
Profile match
Square One Resources is an IT recruitment and IT outsourcing company operating in Poland. Its vacancies cover SAP architecture, full stack and Rust development, DevOps, cybersecurity and IT project management for clients in Warsaw, Krakow and the Tri-City area. The company is based in Warsaw, Poland.
- SIMPL is a European Commission initiative developing an open, modular middleware platform for secure data sharing and interoperability across European data spaces. The project focuses on full-stack development using React, TypeScript, Java 21, Spring, and Kafka, including API development, system integrations, and platform enhancements within an international Agile team.
- The project is currently extended until April 2027.
Zakres obowiązków
- Design, develop, test, and maintain frontend applications using JavaScript, TypeScript, and React.
- Design and implement backend services using Java 21, Spring Framework, Spring Boot, Spring MVC, Spring Integration, and Spring REST.
- Develop and maintain REST APIs and platform integrations.
- Build and support event-driven integrations using Apache Kafka.
- Develop and optimize relational database interactions and queries.
- Create and maintain automated unit tests using JUnit.
- Build and package applications using Maven and deploy them on Tomcat-based environments.
- Ensure code quality through peer reviews, SonarQube analysis, and secure coding practices.
- Address security findings and vulnerabilities identified through Fortify and other security scans.
- Support deployment and operational activities using Argo and Rancher.
- Investigate and troubleshoot technical issues using logs, monitoring, and Elasticsearch.
- Maintain code, configuration, and technical documentation in Git repositories, Jira, and Confluence.
- Contribute to continuous improvement initiatives and engineering best practices within SIMPL.
Wymagania
- Large-scale platform or integration programmes
- 5+ years of professional software development experience
- Proven experience working in Agile / Scrum delivery teams
- Experience using Git, Jira, and Confluence
- English B2/C1
Tech stack
- Java
- JavaScript
- TypeScript
- React.js
- Spring Framework
- Spring Boot
- Apache Spark
- Apache Tomcat
- Apache Flink
- Kafka
- Git
- Jira
- Confluence
- Maven
- JUnit
- Elasticsearch
- ArgoCD
- Docker
- Kubernetes
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