Senior Java Software Engineer - Global Connectivity Platform

1global; Warszawa; Hybrid; PLN 260,000 - 400,000; Full time

Job summary

1GLOBAL, Warsaw-based, is seeking a Senior Java Software Engineer to join the Global Connectivity Platform. You will design, build, and maintain Java backend services, focusing on scalability, resiliency, and security within a fast-growing MVNO context.

You will contribute to architecture decisions, work on legacy modernization and greenfield initiatives, and collaborate in an Agile environment. Fluency in English is essential for collaboration with global teams.

Qualifications

• 5+ years of professional experience in Java backend development.
• Experience with production backend systems.
• Solid understanding of REST APIs, databases, and messaging.
• Experience with unit, integration, and e2e testing.
• Familiarity with CI/CD pipelines and modern development workflows.
• Experience working with Git, Docker, and Kubernetes-based environments.
• Good understanding of cloud services and scalable infrastructure.
• Ability to work independently and take ownership.
• Fluent English (spoken and written).

Responsibilities

• Design, build, and maintain Java backend services.
• Contribute to architecture decisions with focus on scalability, resiliency, and security.
• Work on existing services, legacy modernization, and greenfield initiatives.
• Build and integrate REST APIs.
• Work with messaging systems and data stores.
• Advocate for clean code, testing, and maintainable solutions.
• Participate in code reviews and technical discussions.
• Collaborate closely with your Team Lead and peers.
• Work in an Agile, collaborative environment, contributing to planning and continuous improvement.
• Mentor other engineers when needed.

Skills

Java backend

REST APIs

Databases

Messaging

CI/CD

Git

Docker

Kubernetes

Cloud services

Ownership

English fluency

Tools

Docker

Kubernetes

Git

CI/CD

Job description

Senior Java Software Engineer - Global Connectivity Platform

Technology

Warsaw, Poland

Full-time

1GLOBAL is a profitable, fast-growing business. With full-year revenues in 2025 exceedingUS$200 millionand profits of overUS$25 million, we generate strong cash flows to fund our growth allowing us to continuously invest in infrastructure, platform innovation, and global expansion. Recent years have marked a defining phase in our journey, with major enterprise and mass-consumer client wins accelerating our evolution into a global mobile connectivity powerhouse, purpose-built to enable consumer brands to enter and succeed with their own aspirations to offer telecommunications services to their clients.

Founded in 2022 by experienced technology entrepreneurs,Hakan KoçandPyrros Koussios, 1GLOBAL has rapidly emerged as a European technology leader shaping the future of global telecommunications. We operate as a fully regulated Mobile Virtual Network Operator (MVNO) in 12 countries and as a regulated telecom operator in an additional 28 markets. Headquartered in the Netherlands, with world-class R&D hubs in Lisbon, Berlin, and São Paulo, our team of close to500 experts across 15 countriesis united by a single ambition: to redefine global mobile connectivity through technology, scale, and execution excellence.

About the Team
This is a senior, hands-on Java role focused on scalable backend systems, long-term ownership, and real production challenges.

You’ll join a new backend team in Warsaw working on the evolution of our eSIM, global connectivity platform, and IoT solutions.

The role combines:

• scaling and modernizing existing systems,
• building new services and greenfield components,
• and improving reliability, performance, and maintainability across the platform.

As a senior engineer, you’ll also contribute to introducing and evolving testing approaches as systems grow and change.

Fluency in English is essential for this role, please ensure your CV is submitted in English as part of your application.

About the Role

• Design, build, and maintain Java backend services
• Contribute to architecture decisions with focus on scalability, resiliency, and security
• Work on existing services, legacy modernization, and greenfield initiatives
• Build and integrate REST APIs
• Work with messaging systems and data stores
• Advocate for clean code, testing, and maintainable solutions
• Participate in code reviews and technical discussions
• Collaborate closely with your Team Lead and peers
• Work in an Agile, collaborative environment, contributing to planning and continuous improvement
• Mentor other engineers when needed

Requirements

About You

• 5+ years of professional experience in Java backend development
• Experience working with production backend systems
• Solid understanding of REST APIs, databases, and messaging
• Experience with unit, integration, and e2e testing
• Familiarity with CI/CD pipelines and modern development workflows
• Experience working with Git, Docker, and Kubernetes-based environments
• Good understanding of cloud services and scalable infrastructure
• Ability to work independently and take ownership
• Fluent English (spoken and written)

Why 1GLOBAL?

• Growth Opportunities:Advance your career in one of the fastest growing telecommunications companies, expanding over 100% year-on-year under the leadership of successful tech entrepreneurs.
• Major Transaction Exposure:Be in the driver’s seat for transactions that will have an impact on the future telco industry.
• Work with a Talented Team:From the Board and the Founders to the Senior Management Team, you will collaborate daily with the most capable and renowned external advisors, and constantly being exposed to talented and driven individuals.
• Dynamic Work Environment:Thrive in a collaborative, fast-paced workplace where innovation is encouraged, and every contribution counts.
• Professional Development:Work alongside industry experts to enhance your skills and knowledge in a cutting-edge field.
• International Experience:Gain opportunities to work in different 1GLOBAL offices around the world as you grow within the company.
• Open Communication Culture:Join a team where your ideas are heard, and open dialogue is encouraged, fostering a supportive and transparent work environment.
• Get Things Done Attitude:Be part of a results-driven team that values efficiency, creativity, and the drive to make a tangible impact in the industry.

1GLOBAL is an equal opportunity employer, we value your character as much as your talent. Diversity drives our innovation, and we offer a collaborative, dynamic, and international work environment. We are excited for you to join our mission to revolutionise connectivity globally.

1GLOBAL is a trading name of 1GLOBAL Holdings B.V.