Senior Java Developer

Formula5 is seeking a contract Java Developer to support a 6-8 week engagement delivering a HubSpot-to-Microsoft Entra External ID integration. The senior developer will build a Java Spring Boot microservice deployed on Client's Kubernetes infrastructure, enabling event-driven user provisioning and lifecycle management between HubSpot (system of record) and Entra External ID via Microsoft Graph. Required Skills & Experience Java / Spring Boot - Production-grade microservice development; this is the core of the engagement REST API development - Designing and implementing Create/Update/Disable endpoints; Swagger/OpenAPI documentation Webhook integration - Building and securing inbound webhook receivers (HubSpot webhooks specifically) Microsoft Graph API - Entra External ID user provisioning and lifecycle management (create, update, disable) Docker - Containerization, Dockerfile authoring, Docker Compose for local dev environments Kubernetes - Deployment artifact creation (manifests or Helm); familiarity with Argo CD a plus CI/CD - GitHub Actions for build/packaging pipelines Observability tooling - Loki log exporter configuration; Grafana/Prometheus familiarity Security patterns - Service-to-service authentication, secrets management (API keys, Graph credentials), WAF/API gateway awareness (Imperva, Tyke) Nice to Have Experience with HubSpot API - Contact management operations (create/update/disable, query by CompanyID) Experience with Microsoft Entra External ID / Azure AD B2C Familiarity with React + Java backend portal integrations Prior work in regulated financial services environments