Senior Java Developer (Backend)

You will join a project delivered for a client from the DACH region that is developing a compliance services platform for telecommunications companies. The project is building a multi-tenant, cloud-native SaaS platform from the ground up to handle data production and preservation orders according to the EU e-Evidence Regulation, processing sensitive criminal proceedings data with high security and data residency requirements.

• At least five years of commercial Java development experience
• Very good knowledge of Java and Spring Boot 3
• Hands-on knowledge of Spring Security and Spring Data JPA
• Experience with BPMN workflow engines such as Flowable or Camunda
• Experience embedding a workflow engine within an application or good understanding of the embedded deployment model and shared transactions
• Very good knowledge of PostgreSQL, including query optimisation, indexing strategies, and connection pool management
• Experience designing and developing REST APIs
• Practical knowledge of OpenAPI or Swagger and the specification-first approach
• Experience creating integration tests with Testcontainers
• Knowledge of architectural patterns in multi-tenant SaaS platforms
• Understanding of tenant context propagation, data isolation, and query-scoping mechanisms
• Experience with pull requests, code reviews, and CI-based development processes
• Very good written and spoken English and Polish
• Independence and ownership of implemented solutions, with readiness to work closely with the Lead Software Architect

Nice to have:

• Hands-on knowledge of Flowable, including BPMN or CMMN
• Experience with PostgreSQL Row-Level Security
• Knowledge of ArchUnit and architectural rule testing
• Experience with Keycloak, OIDC, and JWT
• Knowledge of S3 Object Lock or other WORM storage mechanisms
• Experience with Java 21 and virtual threads
• Knowledge of GDPR, compliance, or systems processing legally protected data
• Experience in telecommunications, LegalTech, or GovTech projects
• Knowledge of ETSI TS 103 120 or ETSI TS 104 144 standards
• Practical experience using Claude Code, GitHub Copilot, or other AI-powered coding assistants
• Fluency in German

• Implement BPMN processes in Flowable for the complete EPOC and EPOC-PR case lifecycle
• Configure the Flowable engine as a library embedded within the Spring Boot application using shared database transactions
• Build a multi-tenant data access layer and enforce tenant isolation at the repository and PostgreSQL Row-Level Security levels
• Create ArchUnit tests verifying data access isolation between tenants
• Develop REST APIs for case creation, status queries, and document uploads
• Design API contracts using an OpenAPI specification-first approach
• Integrate the platform with external telecommunications operators’ CRM systems using the adapter pattern
• Implement JWT validation and role-based access control through Keycloak and OIDC integration
• Handle document storage in S3 Object Lock and manage conflicts between GDPR deletion requests and legal preservation holds
• Create integration tests with JUnit 5 and Testcontainers for PostgreSQL, Keycloak, and S3-compatible storage
• Participate in architecture reviews and document technical decisions as Architecture Decision Records
• Use AI-assisted coding tools with mandatory human and automated security code reviews