Senior Java Back-end developer

The opportunity

You'll design and lead the development of cloud-based backend services in modern Java and Spring Boot. Beyond writing high-quality code, you'll drive technical design and architecture, own the reliability and security of your services, and mentor other engineers. Our teams own their services end to end — application code, cloud infrastructure, and delivery pipelines — so a pragmatic engineering-plus-platform mindset is essential.

Day-to-day responsibilities

Core responsibilities

• Lead the design and delivery of new features and services; set the technical direction.
• Own architecture and design decisions: service boundaries, APIs, cross-service contracts, and data models — balancing simplicity, reliability, security, and maintainability.
• Design database schemas and manage evolution through versioned migrations.
• Design and build RESTful APIs and asynchronous/event-driven integrations between services.
• Apply resilience patterns (retries, idempotency, circuit breakers) and champion test-driven development with strong coverage.
• Own delivery: contribute to CI/CD pipelines, containerization, cloud infrastructure, and observability.
• Diagnose complex issues across services and infrastructure; lead incident investigation and resolution.
• Run and participate in code reviews; mentor mid-level and junior developers.

Establish and uphold coding standards, security practices, and design principles across the team

Who are we looking for

Technical knowledge requirements

(Representative — depth in several areas expected, breadth across the rest.)

• Language & Frameworks: Java (LTS), Spring Boot / Spring Framework, Spring Security (OAuth2 / JWT)
• Schema migrations: Flyway or Liquibase
• Cloud & Infrastructure: AWS (or GCP / Azure), Docker, infrastructure-as-code (Terraform / CloudFormation).
• Cloud services (AWS services below, or their GCP/Azure counterparts):
• Container runtime & registry: ECS + ECR
• Object storage: S3 (≈ Cloud Storage / Blob Storage)
• Messaging: SQS (≈ Pub/Sub / Service Bus)
• Database: RDS PostgreSQL (≈ Cloud SQL / Azure Database for PostgreSQL)
• managing and provisioning infrastructure & networking: CloudFormation, IAM, VPC/Security Groups
• Observability: CloudWatch, x-ray
• Messaging: Experience in any kind of messaging system like SQS, Kafka, RabbitMq
• Build & CI/CD: Maven or Gradle, Jenkins (or GitLab CI / GitHub Actions)
• Testing: JUnit, AssertJ, Testcontainers, local cloud emulation (e.g. MinIO, ElasticMQ)
• Observability: distributed tracing, metrics, logging (e.g. OpenTelemetry, X-Ray, CloudWatch, Datadog)
• Version control: Git (Github/Gitlab)
• AI-assisted development: AI coding assistants / CLI tools (Claude Code, GitHub Copilot)

Requirements (Must-Have)

• 4+ years of professional Java development experience
• Experience with modern Java (latest LTS) and a mindset of keeping up with the newest stable language features and tooling.
• Proficiency in Java and object-oriented (and ideally functional) programming principles.
• Strong experience with Spring Boot and the Spring ecosystem, including Spring Security / OAuth2.
• Solid SQL and relational database experience (e.g. PostgreSQL), including schema design and query optimization.
• Experience with a schema migration / database versioning tool (e.g. Flyway, Liquibase).
• Proven experience designing and building RESTful APIs and integrating distributed services.
• Experience with containers (e.g. Docker) and CI/CD pipelines (e.g. Jenkins, GitLab CI, GitHub Actions).
• Strong experience with automated testing — unit and integration (e.g. JUnit, Testcontainers).
• Solid grasp of software architecture and design patterns (e.g. clean/hexagonal architecture, DDD).
• Solid Understanding of secure coding, resilience, and observability in production systems.
• Confident use of Git and modern branching/merging workflows.
• Ability to lead in an Agile environment and to mentor other developers.
• Experience with AI-assisted development — using AI coding assistants / CLI tools and awareness of prompting, context windows, and token cost.
• Able to design and implement asynchronous / event-driven integrations correctly (messaging, idempotent consumers, ordering, retries/dead-letter handling, eventual consistency) — including in projects where they are used only occasionally.
• Proficiency in English.

Perks & Benefits

At Worldline you’ll get the chance to be at the heart of the global payments technology industry and shape how the world pays and gets paid. On top of that, you will also:

• Private medical & life insurance
• MyBenefit Platform
• Holiday allowance
• Public transportation allowance
• Meal allowance
• Annual bonus.

We are proud to be an Equal Opportunity employer. We do not discriminate based upon race, religion, color, national origin, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as an individual with a disability, or any applicable legally protected characteristics.

Pursuant to the Article 24 sec. 6 of the Act of 14 June 2024 on the protection of whistleblowers, we inform you that Worldline Financial Services (Europe) S.A., a joint-stock company, Branch in Poland (hereinafter referred to as Worldline) is governed by the Regulations on the receipt of internal reports and taking follow-up actions (hereinafter referred to as the Regulations).

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