Senior Back End Software Engineer (Java + PHP)

United States Digital Space LLC; Ozorków; Hybrid; PLN 180,000 - 280,000; Full time

Benefits offered by this job

International projects

Hybrid/remote flexibility

Medical healthcare

Recognition program

Learning reimbursement

Well-being program

Team events

Sports compensation

Referral bonuses

Equipment provision

Job summary

United States Digital Space LLC is seeking a backend engineer to design, build, and maintain scalable services in a Java/PHP environment. You will work on a high-visibility Search platform used across multiple countries.

You will collaborate with Product, Frontend, Data, UX, and other engineering teams, own components end-to-end, and help migrate PHP services to Java, improving performance and reliability. Experience with distributed systems and cloud tech is essential.

Qualifications

• Solid professional backend development experience.
• Strong expertise in Java and JVM frameworks (Micronaut/Spring Boot).
• Experience with PHP in a mixed Java/PHP environment.
• Experience with Kubernetes, AWS, MySQL, and Kafka.
• Strong understanding of distributed systems, scalability, reliability, and software architecture.
• Experience building scalable systems handling high volumes of requests and data.
• Experience with unit and integration testing.
• Strong problem-solving, communication, and collaboration skills.
• Experience working in Agile, cross-functional teams.

Responsibilities

• Design, develop, and maintain scalable, reliable, and high-performance backend services.
• Build and evolve the Search platform handling millions of search requests per day across 40+ countries.
• Design components and integrations with a focus on scalability, maintainability, reliability, and performance.
• Work on complex distributed systems problems including graph-based search, caching, memory optimization, and high-throughput processing.
• Contribute to migration of Search services from PHP to Java, improving performance and caching.
• Drive technical improvements and contribute to architecture and technology decisions.
• Ensure backend services are observable and design effective monitoring strategies.
• Identify, prioritize, and reduce technical debt with the team.
• Support and improve CI/CD processes and ensure high-quality releases.
• Write SOLID, maintainable, testable, and scalable code.
• Collaborate with Product, Frontend, Data, UX, and other Engineering teams.
• Participate in code reviews, mentoring, and knowledge sharing.
• Lead adoption of better engineering practices and improve team workflows.
• Take ownership of backend solutions from concept to production.

Skills

Backend development

Java & JVM

PHP experience

Kubernetes

AWS

MySQL

Kafka

Distributed systems

Unit & integration testing

Agile / cross-functional

Tools

OpenSearch/Elasticsearch

GitLab CI/CD

Terraform

Job description

Why Join the company

We’re an AI-first global tech company with 25+ years of engineering leadership, 2,000+ team members, and 500+ active projects powering Fortune 500 clients, including HBO, Microsoft, Google, and Starbucks.

From AI platforms to digital transformation, we partner with enterprise leaders to build what’s next.What powers it all? Our people are ambitious, collaborative, and constantly evolving.

About the Client

An international transportation technology company focused on building scalable digital solutions for modern rail operations. The organization develops internal platforms and automation tools that improve operational efficiency, support business growth, and streamline complex processes in a fast-paced environment.

Project Tech Stack

Java, JVM, Micronaut, Spring Boot, PHP, Symfony, Kubernetes, AWS, MySQL, Kafka, OpenSearch / Elasticsearch, Redis, Terraform, GitLab CI/CD, Unit Testing, Integration Testing, Distributed Systems.

What You'll Do

• Design, develop, and maintain scalable, reliable, and high-performance backend services.
• Build and evolve the Search platform handling millions of search requests per day across 40+ countries.
• Design components and integrations with a strong focus on scalability, maintainability, reliability, and performance.
• Work on complex distributed systems problems, including graph-based search, caching, memory optimization, and high-throughput processing.
• Contribute to the migration of Search services from PHP to Java, improving performance, throughput, parallelism, and caching.
• Drive technical improvements and contribute to architecture and technology decisions.
• Ensure backend services are observable and design effective monitoring strategies for new components.
• Identify, prioritize, and reduce technical debt together with the team.
• Support and improve CI/CD processes and ensure high-quality, reliable releases.
• Write SOLID, maintainable, flexible, testable, and scalable code.
• Collaborate closely with Product, Frontend, Data, UX, and other Engineering teams.
• Participate in code reviews, technical discussions, mentoring, and knowledge sharing.
• Lead the adoption of better engineering practices and improve team development workflows.
• Take ownership of backend solutions from concept and design through implementation and production.

What You Bring

• Solid professional backend development experience
• Strong expertise in Java and JVM-based frameworks such as Micronaut or Spring Boot
• Professional experience with PHP and willingness to work in a mixed Java/PHP environment
• Experience with Kubernetes, AWS, MySQL, and distributed messaging systems such as Kafka
• Strong understanding of distributed systems, scalability, reliability, and software architecture
• Experience building scalable systems handling high volumes of requests and data
• Experience with unit and integration testing
• Strong problem-solving, communication, and collaboration skills
• Experience working in Agile, cross-functional teams

Nice to Have

• Experience with OpenSearch / Elasticsearch
• Knowledge of Redis and Terraform
• Experience with Symfony
• Familiarity with GitLab CI/CD
• Experience with observability and monitoring
• Knowledge of graph theory or search optimization

English level

Upper-Intermediate

Legal & Hiring Information

• the company is proud to be an Equal Opportunity Employer committed to inclusion across minority, gender identity, sexual orientation, disability, age, and more.
• Reasonable accommodations are available to enable individuals with disabilities to perform essential functions.
• Please note: this job description is not exhaustive. Duties and responsibilities may evolve based on business needs.
• Compensation details are shared with candidates at the early stage of the recruitment process.
• The offer is not binding until a signed contract is in place.

Your Benefits at the company

the company benefits vary by location and contract type. Your recruiter will fill you in on the details.

• International projects
• In-office, hybrid, or remote flexibility
• Medical healthcare
• Recognition program
• Ongoing learning & reimbursement
• Well-being program
• Team events & local benefits
• Sports compensation
• Referral bonuses
• Top-tier equipment provision

the company Culture

We lead with trust, respect, and purpose. We believe in open dialogue, creative freedom, and mentorship that helps you grow, lead, and make a real difference. Ours is a culture where ideas are challenged, voices are heard, and your impact matters.