Senior Fullstack Software Engineer (Java & React)

Role summary

Senior Fullstack Software Engineer (Java & React) is a role at Inetum in Warsaw, Masovian Voivodeship, Poland (hybrid). Posted 2026-10-20. Experience level: 5-10.

Job title

Senior Fullstack Software Engineer (Java & React)

Company

Inetum

Location

Warsaw, Masovian Voivodeship, Poland

Work arrangement

hybrid

Category

Software Engineering

Experience level

5-10

Date posted

2026-10-20

Job description

Company Description

Inetum Polska is part of the global Inetum Group and plays a key role in driving the digital transformation of businesses and public institutions. Operating in cities such as Warsaw, Poznan, Katowice, Lublin, Rzeszow, Lodz the company offers a wide range of IT services. Inetum Polska actively supports employee development by fully funding training, certifications, and participation in technology conferences. Additionally, the company is involved in local social initiatives, such as charitable projects and promoting an active lifestyle. It prides itself on fostering a diverse and inclusive work environment, ensuring equal opportunities for all.

Globally, Inetum operates in 19 countries and employs over 28,000 professionals. The company focuses on four key areas:

Consulting (Inetum Consulting): Strategic advisory services that help organizations define and implement innovative solutions.

Infrastructure and Application Management (Inetum Technologies): Designing and managing IT systems tailored to clients’ individual needs.

Software Implementation (Inetum Solutions): Deploying partner solutions from industry leaders like Microsoft, SAP, Salesforce, and ServiceNow.

Custom Software Development (Inetum Software): Creating unique software solutions to meet specific client needs.

With strategic partnerships with major technology giants, including Microsoft, SAP, Salesforce, and ServiceNow, Inetum delivers advanced technological solutions tailored to customer requirements. In 2023, Inetum reported revenues of €2.5 billion, underscoring its strong position in the digital services market.

Inetum distinguishes itself by offering a comprehensive range of benefits that meet the diverse needs of employees, providing flexibility, support and commitment. Here's what makes working at Inetum unique:

Flexible and hybrid work:

Flexible working hours.

Hybrid work model, allowing employees to divide their time between home and modern offices in key Polish cities.

Attractive financial benefits:

A cafeteria system that allows employees to personalize benefits by choosing from a variety of options.

Generous referral bonuses, offering up to PLN6,000 for referring specialists.

Additional revenue sharing opportunities for initiating partnerships with new clients.

Professional development and team support:

Ongoing guidance from a dedicated Team Manager for each employee.

Tailored technical mentoring from an assigned technical leader, depending on individual expertise and project needs.

Community and Well-Being:

Dedicated team-building budget for online and on-site team events.

Opportunities to participate in charitable initiatives and local sports programs.

A supportive and inclusive work culture with an emphasis on diversity and mutual respect.

Job Description

We are looking for a Senior Fullstack Software Engineer (Java & React) to join a team developing a large-scale digital commerce platform based on microservices and micro-frontends .

You will work end-to-end with Java 25, Spring Boot 4, Spring WebFlux, React, TypeScript and Kubernetes , building new features, integrating backend services and helping modernize the existing platform through legacy migration and technical debt reduction.

A key part of the project is AI-driven development , with coding agents and GitHub Copilot becoming part of everyday engineering. We are looking for someone who actively uses AI coding tools and is interested in shaping how they can improve software development.

Main tasks

Develop and evolve a distributed online platform based on microservices and micro-frontends .

Take end-to-end ownership of features , working across both 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 new platform features and support the migration of legacy applications to the modern architecture.

Improve the existing codebase through refactoring, technical debt reduction and resolution of long-standing technical issues .

Contribute to the adoption of new API standards, including TM Forum Open APIs .

Work with containerized applications using Kubernetes and Docker , including deployment, operation, monitoring and troubleshooting.

Use AI coding agents and AI-assisted development workflows as part of your daily work and contribute to improving these practices within the team.

Work on multiple initiatives of different sizes, from short tasks to larger projects.

Participate in knowledge-transfer activities, keep technical documentation up to date and actively share knowledge with other developers.

Qualifications

Requirements

Several years of professional experience in developing modern web applications, with strong backend expertise and the ability to work independently at Senior level.

Strong practical knowledge of Java 8+ and Spring Boot , as well as REST API design with JSON.

Familiarity with current versions of the Java/Spring ecosystem and a strong understanding of reactive programming , supported by hands-on experience with Spring WebFlux, Project Reactor or a comparable reactive stack .

Hands-on frontend experience with React, TypeScript, JavaScript, HTML and NPM , with the confidence to work 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 experience with Kubernetes and Docker , including deployment, operation, monitoring and troubleshooting of containerized applications in cloud-native environments.

Experience developing and evolving microservice-based and distributed systems , including wo