Python/FastAPI Developer for Backend Fixes

We have an existing Python/FastAPI backend that is already in production, but we are experiencing several reliability and performance issues. We need an experienced backend developer who can review the existing codebase, identify the root causes, and make targeted fixes without rebuilding the application. Current Issues Third-party API requests occasionally fail or timeout Retry handling is unreliable Duplicate records sometimes appear in PostgreSQL One synchronization endpoint becomes slow with larger datasets Background processing can stop after external API failures Some endpoints occasionally return HTTP 500 errors Error logging does not provide enough information PostgreSQL connection/session handling may have concurrency issues Redis/background processing needs reliability review What You Will Do Debug the existing FastAPI backend Identify root causes of current production issues Fix API timeout and retry logic Prevent duplicate PostgreSQL records Optimize slow database queries and API workflows Fix background synchronization failures Improve async/concurrent request handling Improve exception handling and structured logging Review SQLAlchemy database sessions Review Redis usage where necessary Test fixes and confirm existing functionality remains stable Document the problems found and fixes implemented Tech Stack Python FastAPI PostgreSQL SQLAlchemy Redis REST APIs Third-Party API Integrations Docker Git Required Skillsets Primary Skills Python FastAPI PostgreSQL RESTful API API Development Back-End Development SQLAlchemy Backend Debugging Performance Optimization Docker Additional Relevant Skills Redis API Integration Async Python Database Architecture Database Optimization Microservices Error Handling Background Jobs Data Processing Git Preferred Experience Experience with some of the following is a plus: Celery RabbitMQ Apache Kafka Webhooks Pandas ETL pipelines AWS Kubernetes OAuth2 / JWT Production monitoring and observability Expected Result After completion: API synchronization should run reliably Temporary API failures should retry safely Duplicate database records should be eliminated HTTP 500 errors should be resolved PostgreSQL performance should improve Background processing should recover from failures Logging should clearly identify future production issues Existing functionality should remain unchanged Deliverables Root-cause analysis of the existing issues Fixed FastAPI backend code PostgreSQL/data consistency fixes Improved API retry and timeout handling Performance optimization Improved logging and exception handling Testing of all affected functionality Short technical summary of the fixes We are specifically looking for someone comfortable working inside an existing production backend, diagnosing problems systematically, and making clean, targeted fixes. Please briefly describe a similar Python/FastAPI backend issue you have fixed and how you identified the root cause.