Java Software Engineer

🚀 Senior Java Developer

Company: Roslin Global Solutions

Location: Bucharest, Romania – Pipera area

Work Arrangement: Full-time, office-based

Collaboration Type: Official Employment or B2B

🌍 About Roslin Global Solutions

Roslin Global Solutions is an international business services company supporting a diverse portfolio of projects and brands operating primarily in the United States.

We are looking for an experienced Senior Java Developer with a strong background in payment systems to help improve the reliability of our payment services.

Your focus will be rewriting selected payment microservices from Go (Golang) to Java , ensuring accurate transaction processing, consistent financial data, and dependable service behavior. Our platform services and performance-critical paths will continue to use Go.

🎯 About the Role

The Senior Java Developer will develop and maintain Java services responsible for payment workflows, with reliability and correctness at the center of every technical decision.

You will analyze existing Go implementations, understand their business logic and failure scenarios, and deliver Java replacements that integrate with our existing infrastructure.

Our services communicate through gRPC using Protocol Buffers (proto3) and use NATS JetStream for messaging.

The ideal candidate has hands-on experience with payment systems, understands distributed transaction processing, and can take ownership of services through development, testing, and production support.

You will collaborate with DevOps on deployment and operation. DevOps will handle most infrastructure work, but practical experience with AWS or GCP and Kubernetes is required.

This role requires full-time availability to work from our Bucharest office in the Pipera area.

📌 Key Responsibilities

• Analyze existing payment microservices written in Go, including transaction flows, dependencies, and failure scenarios.
• Rewrite selected payment services in Java, preserving business logic and improving reliability.
• Develop dependable payment workflows with appropriate transaction state management and recovery mechanisms.
• Implement idempotency, deduplication, retries, and reconciliation to prevent duplicate processing and inconsistent financial records.
• Design and maintain gRPC interfaces and proto3 contracts.
• Maintain compatibility between Java payment services and existing Go services.
• Build and support event-driven workflows using NATS JetStream.
• Handle message acknowledgments, redelivery, ordering requirements, and processing failures.
• Work with databases to maintain transaction integrity, auditability, and data consistency.
• Write automated tests covering payment behavior, service contracts, failure scenarios, and recovery.
• Implement useful logging, metrics, tracing, and alerts for payment services.
• Plan and validate service migrations, including rollout and rollback procedures.
• Collaborate with DevOps on deploying services to AWS or GCP using Kubernetes.
• Support application configuration, health checks, troubleshooting, and operational readiness.
• Investigate production issues and help address their root causes.
• Document payment flows, service behavior, technical decisions, and operational procedures.
• Collaborate with developers, QA specialists, project managers, and other stakeholders.

✅ Required Qualifications

• Substantial professional experience developing production backend services in Java .
• Hands-on experience building or maintaining payment systems , such as payment processing, payouts, refunds, transaction ledgers, or reconciliation.
• Strong understanding of payment reliability, including idempotency, duplicate prevention, transaction states, and recovery from partial failures.
• Experience with microservices and distributed systems.
• Practical experience with gRPC and Protocol Buffers , including proto3 contracts and compatibility.
• Experience with messaging systems and reliable asynchronous processing.
• Strong knowledge of relational databases, SQL, transactions, and data consistency.
• Ability to read and understand Go code and translate existing payment logic into Java.
• Experience writing meaningful unit and integration tests.
• Familiarity with Git, code reviews, and CI/CD workflows.
• Practical experience deploying or supporting backend services in AWS or Google Cloud Platform (GCP) , including managed services, configuration, permissions, and monitoring.
• Hands-on experience with Kubernetes , including deploying, configuring, and troubleshooting containerized services in collaboration with DevOps.
• Strong problem-solving skills and the ability to investigate unfamiliar systems.
• Clear communication, ownership of deliverables, and professional fluency in English.
• Availability to work full-time from our Bucharest office in the Pipera area.

⭐ Preferred Qualifications

• Hands-on experience with NATS JetStream .
• Experience with Kafka or comparable messaging platforms, particularly in payment workflows.
• Previous experience migrating payment services between programming languages.
• Production development experience with Go.
• Experience with Spring Boot or comparable Java backend frameworks.
• Experience integrating payment providers and handling asynchronous payment status updates.
• Familiarity with financial reconciliation, audit trails, and ledger design.
• Experience with Docker and managed Kubernetes platforms such as Amazon EKS or Google Kubernetes Engine (GKE) .
• Familiarity with observability tools, load testing, and failure testing.
• Experience working in an international or multi-project environment.

📊 What Success Looks Like

During the first year, the Senior Java Developer will be expected to:

• Build a clear understanding of existing payment flows, service dependencies, and reliability risks.
• Deliver agreed payment service migrations from Go to Java.
• Preserve transaction correctness and compatibility with existing services.
• Establish reliable handling of retries, duplicate messages, and partial failures.
• Strengthen automated testing of payment workflows and recovery scenarios.
• Improve visibility into transaction status, processing failures, and reconciliation issues.
• Work with DevOps to ensure services are ready for deployment and ongoing operation.
• Produce clear documentation that supports maintenance and incident resolution.

🎁 What We Offer

• Responsibility for payment services where reliability and correctness have a direct business impact.
• Direct collaboration with company leadership and project stakeholders.
• The opportunity to influence payment service architecture, engineering standards, and reliability practices.
• Exposure to several industries and business models.
• Access to modern development technologies and AI-supported workflows.
• Professional growth in an international and multicultural environment.
• Long-term collaboration through official employment or a B2B agreement.
• A newly opened office hub in Bucharest’s Pipera area.

🏢 Working Arrangement

This is a full-time, office-based position at our newly opened hub in the Pipera area of Bucharest .

Collaboration is available under Official Employment or on a B2B basis .

📩 How to Apply

Click the Apply button to access our official vacancy application form through PeopleForce .

Please complete all required fields and provide:

• Your CV.
• A summary of your Java and payment systems experience.
• Details of your experience with gRPC, messaging systems, AWS or GCP, and Kubernetes.
• Examples of payment reliability challenges or service migrations you have worked on.
• Links to your GitHub profile, portfolio, or relevant projects, if available.
• Your availability to start and work from our Bucharest, Pipera office.

Only applications submitted through the PeopleForce vacancy application form will be considered.

💬 Ready to Join?

Click Apply , complete the application form, and tell us how your Java and payment systems experience can help us build more reliable payment services.