Java Spring Boot & Kafka Architecture Review

We are looking for an experienced Java/Spring Boot architect or senior backend engineer to review and evaluate an enterprise backend architecture. The goal is to assess the current design, identify architectural gaps, and provide practical recommendations for building a scalable, secure, maintainable, and reliable distributed system. The ideal candidate should have strong hands-on experience with: Java + Spring Boot + Microservices + Apache Kafka + PostgreSQL + Keycloak Experience with Camunda, Redis, Debezium, Kubernetes, and observability is highly desirable. Areas to Review The review should cover the relevant parts of the system architecture, including: Microservice boundaries and responsibilities Spring Boot service architecture API Gateway design REST API communication Apache Kafka architecture Kafka topics and event design Producer/consumer relationships Event schemas Consumer groups and partitioning Retry and failure-handling strategies Idempotency Database ownership and PostgreSQL design Redis caching strategy Authentication and authorization Keycloak integration Spring Security Camunda/workflow integration Inter-service communication Scalability and performance Fault tolerance Observability and monitoring Deployment architecture Expected Deliverables 1. Architecture Assessment Provide your understanding of the current architecture and explain the responsibilities of the major components. 2. Architecture Diagram Provide a clear high-level architecture diagram showing the major services, databases, Kafka, authentication, and external integrations. 3. Architectural Findings Identify important issues or risks, such as: Incorrect service boundaries Tight coupling Kafka design problems Data consistency concerns Security weaknesses Scalability bottlenecks Failure-handling gaps Unnecessary architectural complexity 4. Recommended Architecture Provide practical recommendations for improving the architecture and explain the reasoning behind the proposed design. 5. Kafka/Event-Driven Design Review or propose: Kafka topics Events Producers and consumers Event ownership Partitioning strategy Consumer groups Retry strategy Dead-letter handling Idempotency 6. Security Architecture Review the authentication and authorization approach, particularly: Keycloak → OAuth 2.0/OIDC → JWT → Spring Security → Microservices 7. Technology Recommendations Provide recommendations around technologies such as: Kafka vs synchronous REST Redis caching Camunda workflow orchestration Debezium CDC PostgreSQL Kubernetes Ideal Candidate We are looking for someone with practical experience designing or reviewing: Java/Spring Boot microservices Event-driven architectures Apache Kafka Distributed systems PostgreSQL Keycloak / Spring Security Enterprise backend systems Experience with financial, payment, banking, government, or other transaction-heavy systems is a strong advantage. Application Questions Please answer the following in your proposal: How many years of experience do you have with Java/Spring Boot? Have you designed production Kafka architectures? Please provide an example. Have you designed microservice boundaries for an existing system? What is your experience with Keycloak and OAuth2/OIDC? Have you worked with Camunda or another workflow engine? How would you approach reviewing a Spring Boot + Kafka architecture within a 5–7 hour engagement? Please provide one example of an architectural problem you identified and how you improved it. Scope This is a focused one-time architecture review with an estimated effort of 5–7 hours. The objective is to quickly understand the existing system, identify the most important architectural considerations, and provide clear, actionable recommendations and design documentation. Fixed Budget: $85