Senior Java Backend Developer

Join a Unified Commerce engineering squad as a Senior Java Backend Developer, on a freelance basis through Shakers . Shakers connects senior independent talent with product companies across Europe - this is a freelance engagement, not an in-house hire, and the client is disclosed once you're through initial screening.

What you'll own:

• Lead design and implementation of complex Java microservices across Unified Commerce products
• Define and enforce architectural patterns, coding standards, and security practices for the squad
• Own IAM strategy: Keycloak realm design, Okta federation, OIDC flow architecture
• Drive technical discussions with product owners and architects, representing engineering
• Identify and resolve performance bottlenecks, scalability issues, and security vulnerabilities
• Lead code reviews and establish quality gates; champion SonarQube and Snyk adoption
• Mentor confirmed and junior engineers
• Produce technical documentation, ADRs, and runbooks

What we're looking for:

• 8+ years of software engineering experience
• Expert-level Java and Spring/Spring Boot
• Advanced microservices architecture experience
• Hands-on with Amazon SQS, Docker, Kubernetes, MongoDB, MySQL
• Experience with Keycloak, Okta, OIDC
• Familiarity with SonarQube and Snyk
• English C1, Portuguese C1
• Available hybrid, 3 days/week on-site in Lisbon