Backend Developer

At Icalia Labs, we partner with engineering-driven organizations building large-scale, production-critical systems in regulated industries. We are currently hiring a Full Stack Engineer — Integration / Spring Boot for a healthcare SaaS platform building enterprise-grade integrations and API infrastructure.Role OverviewWe are looking for a backend engineer to join a team focused on building enterprise-grade integrations and API infrastructure. You will design secure REST APIs, implement event-driven services for asynchronous communication, and deliver reusable connector frameworks that integrate with major enterprise platforms. The work emphasizes microservices architecture, AWS cloud-native services, and engineering rigor around idempotency, observability, and security.ResponsibilitiesDesign, build, and maintain backend microservices in Java and Spring Boot to expose secure, well-versioned REST APIs.Build and operate event-driven services that enable asynchronous communication with third-party systems, applying patterns for idempotency, retry handling, and back pressure under at-least-once delivery guarantees.Implement and validate JWT-based authentication flows, including signature validation and identity provider integration.Deploy services on AWS using ECS Fargate, ALB, RDS, S3, EventBridge, CloudWatch, and IAM to ensure scalability, security, and operational visibility.Write unit and integration tests as part of every feature; contribute to the team's automated test coverage standards.Participate in architecture discussions, identify reusable patterns across integrations, and help evolve the integration layer so that one connector can serve multiple use cases instead of building bespoke implementations.Must-Have SkillsJava 17 or Java 21 with 5+ years of professional experienceSpring Boot 3.x with hands-on production experienceSpring Security configured from scratch (filter chains, JWT validation)JPA / HibernateRESTful API design, versioning, validation, and error handlingMicroservices architecture in productionJWT-based authentication: end-to-end understanding including signature validation (HMAC or RSA) and HTTP-only cookie storageDependency Injection in Spring with practical understanding of testability benefits (mock injection)Event-driven architecture: idempotency, at-least-once delivery, message ordering, back pressure handlingAWS production experience with: ECS Fargate, RDS, ALB, EventBridge, S3, CloudWatch, and IAMAWS Cognito or equivalent identity provider integrationMySQL: schema design, indexing, and query optimizationUnit testing with JUnit and MockitoDockerGit workflow proficiencyB2+ English proficiency — daily communication, technical discussions, and code reviews are in EnglishNice-to-Have SkillsKafka (transferable conceptual foundation for EventBridge)Terraform for Infrastructure as CodeSpring Batch for high-throughput data processingAPI integrations with enterprise systems (NetSuite, Salesforce, Business Central)Experience in regulated industries (healthcare, fintech, insurance)Out of Scope for This Role Migrating frontend frameworks, building UI component libraries, or leading Angular modernization efforts.DetailsEngagement type: Independent contractor — staff augmentationIdeal start date: Mid-JuneInitial 3-month contract with high possibility of extensionRemote — LATAMIdeal CandidateCurrently working with Java and Spring Boot in production, with real experience securing APIs and building event-driven systems. You understand integration engineering deeply: idempotency strategies, at-least-once delivery guarantees, JWT validation end-to-end, and AWS cloud-native deployments. You can design a connector framework that serves multiple use cases without over-engineering, and you write tests as part of your normal delivery process — not as an afterthought.If your background aligns closely with this stack, we'd be glad to connect!Pre-Employment Verification & Compliance NoticeAll candidates who advance through Icalia Labs' selection process are subject to a standardized pre-employment due diligence procedure applied uniformly and without exception. This process includes verification of government-issued identification, professional background screening, and direct confirmation of employment history. Candidates selected to move forward will be required to submit professional references, verified directly with the referenced parties at the final stages of the process, in compliance with applicable labor, privacy, and data protection regulations. Any material discrepancy between information provided and verified records will result in disqualification.Icalia Labs is an equal opportunity employer. All qualified applicants are evaluated solely on professional merit, qualifications, and demonstrated experience.