Senior Backend Software Engineer (m/f/n)

This role supports a long-term eDelivery project delivered for the European Commission by Shimi Sp. z o.o.

• At least 8 years experience with backend languages and frameworks: Java, Jakarta EE, Spring/Spring Boot, Hibernate.
• At least 7 years in build and dependency management tools: Maven, Gradle, npm.
• At least 5 years with relational databases: Oracle DB, PostgreSQL, MySQL.
• At least 5 years working with REST APIs and/or SOAP/WSDL web services.
• At least 5 years with message brokers: ActiveMQ, RabbitMQ, Kafka.
• At least 5 years working with message formats and standards: XML, XSD, XPath, WSDL, JSON, JSON Schema.
• At least 5 years experience with Git and Git workflows (GitFlow, trunk-based development).
• At least 1 year experience with distributed transaction patterns and idempotency.
• English language proficiency: minimum B2 level.

Nice to have:

• Experience with eDelivery standards and profiles: OASIS ebMS3, AS4, SMP, BDXL, ebCore PartyId.
• Experience with security protocols, web application security, and secure API design including TLS/SSL, mTLS, PKI, HTTPS, WS-Security, CSP, OAuth 2.0, OpenID Connect, JWT, SAML, OWASP mitigations, and secrets management tools like HashiCorp Vault, AWS Secrets Manager.
• Experience in JVM profiling, resolving thread contention and connection pool issues, Liquibase/zero-downtime database migrations, code reviews, static analysis (SonarQube), and technical debt management.
• Experience with integration protocols, enterprise messaging patterns, service discovery, circuit breakers, load balancing, and containerization (Docker).
• Familiarity with CI/CD pipelines (Bamboo, GitLab CI, GitHub Actions), Infrastructure-as-Code (Terraform, Ansible), and monitoring/telemetry tools (Dynatrace, Splunk, Elastic APM, OpenTelemetry).
• Experience with Python or Node.js, Java software architecture or enterprise software development certifications.
• Experience working for European institutions, public administration, or large international organizations.
• French language skills (B2+).

• Contribute to development of eDelivery products (Domibus, DomiSMP, DomiSML, eDelivery Conformance Testing Platform) in coordination with Technical Architects.
• Develop and maintain backend services, write clean, maintainable code, and implement unit/integration tests integrated into CI/CD pipelines.
• Design distributed transaction patterns including idempotency, duplicate detection, reliable message delivery, eventual consistency, and compensating transactions.
• Implement authentication and authorization flows, mTLS, secrets management, HSM integration, threat modeling, and versioned REST/SOAP APIs with contracts (OpenAPI, WSDL).
• Design message broker topologies for inter-service communication using standard protocols (AS4, ebMS3).
• Optimize performance and scalability, profile database queries, resolve contention points, and design data storage solutions (partitioning, sharding, zero-downtime migrations).
• Implement structured logging, distributed tracing, metrics collection, participate in post-mortems, write technical documentation, and configure cloud services.

The candidate must be located within the EU.