Senior Fullstack Software Engineer (Java & React)

Inetum Polska

About The Position

Inetum Polska is seeking a Senior Fullstack Software Engineer to join a team building a large-scale digital commerce platform using microservices and micro-frontends. The role works across the stack with Java 25, Spring Boot 4, Spring WebFlux, React, TypeScript, and Kubernetes to deliver features, integrate backend services, and modernize the platform through legacy migration and technical debt reduction. AI-driven development is a key part of the project, with coding agents and GitHub Copilot used in everyday engineering. The engineer will take end-to-end ownership of features within services, working on backend APIs and integrations as well as frontend functionality. The work includes containerized application deployment and operations, platform modernization, adoption of API standards such as TM Forum Open APIs, and collaboration across multiple initiatives. The role also involves maintaining technical documentation, knowledge transfer, and sharing expertise with developers. This position offers a hybrid or remote work model. Office locations are Warszawa, Poznań, and Lublin.

Requirements

Several years of professional experience developing modern web applications, strong backend expertise, and the ability to work independently at Senior level.
Strong practical knowledge of Java 8+ and Spring Boot, and REST API design using JSON.
Familiarity with current Java and Spring ecosystem versions and a strong understanding of reactive programming, with hands-on experience in Spring WebFlux, Project Reactor, or a comparable reactive stack.
Hands-on experience with React, TypeScript, JavaScript, HTML, and NPM, and confidence working across frontend and backend within the same service.
Experience with JUnit, Mockito, WireMock, Git, JPA/Hibernate, and XML processing technologies such as XSLT, XPath, and XQuery.
Hands-on Kubernetes and Docker experience, including deployment, operation, monitoring, and troubleshooting of containerized applications in cloud-native environments.
Experience developing and evolving microservice-based and distributed systems, including work with established, long-running codebases.
Practical experience with AI-driven software development, such as GitHub Copilot, OpenCode, coding agents, context management, harness engineering, or spec-driven development.
Regular use of AI coding agents, including adapting prompts or skills and using AI to generate a meaningful part of code; ability to explain how these tools improve the development workflow.
Ability to own features from design through production and make sound technical decisions within a distributed architecture.
Proactive, analytical, quality-oriented approach focused on continuous improvement and practical problem-solving.
Willingness to challenge existing approaches, contribute ideas, review code, share knowledge, and support other developers.
Ability to work effectively in an Agile, distributed, and international environment.
Written and spoken English and Polish at minimum B2 level.

Nice To Haves

Experience with micro-frontend architectures.
Knowledge of Helm charts and Jenkins CI/CD pipelines.
Experience with headless or content-driven systems, particularly NEOS CMS.
Experience migrating legacy applications to modern platforms.
Experience with larger refactoring and technical debt reduction initiatives.
Previous experience working in distributed, multinational, and remote teams.
Knowledge of BDD and test automation beyond unit testing, such as Playwright.

Responsibilities

Develop and evolve a distributed online platform based on microservices and micro-frontends.
Take end-to-end ownership of features across backend and frontend within the same service.
Build and maintain backend services using Java, Spring Boot, and Spring WebFlux, including REST APIs and integrations with internal and backend systems.
Develop frontend functionality using React, TypeScript, JavaScript, HTML, and NPM.
Work with content delivered through a CMS and related content delivery services.
Implement platform features and support migration of legacy applications to the modern architecture.
Refactor the codebase, reduce technical debt, and resolve longstanding technical issues.
Contribute to adoption of API standards, including TM Forum Open APIs.
Deploy, operate, monitor, and troubleshoot containerized applications using Kubernetes and Docker.
Use AI coding agents and AI-assisted workflows in daily work and help improve these practices within the team.
Work on initiatives of varying sizes, from short tasks to larger projects.
Participate in knowledge transfer, maintain technical documentation, and share knowledge with other developers.

Benefits

Flexible working hours.
Hybrid work model allowing employees to divide time between home and modern offices in key Polish cities.
Cafeteria system with a choice of benefits.
Referral bonuses of up to PLN 6,000.
Revenue-sharing opportunities for initiating partnerships with new clients.
Dedicated Team Manager guidance.
Tailored technical mentoring from an assigned technical leader.
Team-building budget for online and on-site events.
Opportunities to participate in charitable initiatives and local sports programs.
Inclusive work culture emphasizing diversity and mutual respect.
Fully funded training, certifications, and participation in technology conferences.