Andrei H.

I build and fix production backend systems — APIs, microservices, databases, integrations and AI-powered services — primarily using Go, Python/FastAPI and PHP. I've been developing production software for 15+ years, including 11 years working on a multi-cloud marketplace and billing platform acquired by Google. The platform processes millions of dollars in monthly billing for tens of thousands of businesses and close to 100,000 users, backed by a 7 TB MySQL database and BigQuery reporting pipelines. I own backend services there end to end: Go microservices using gRPC and REST, usage rating and invoicing pipelines for AWS, Azure and Google Cloud, database schema design, query optimization on high-volume billing tables, and the Angular/TypeScript applications on top. What I can help you with: Backend services, REST APIs and microservices in Go, Python/FastAPI or PHP Debugging existing systems — from straightforward bugs to race conditions, performance issues and production data problems MySQL schema design, indexing, query optimization and safe migrations Third-party APIs, payments, billing and external service integrations AI/LLM integrations, agents, tool calling, MCP and RAG systems BigQuery pipelines, reporting and large-scale data processing Full-stack work when needed using Angular and TypeScript Dockerized applications and production deployments I'm also a co-founder of FranceRent, a live tours and experiences marketplace in France handling around 100 bookings per month. I built its entire backend and full administration platform, including the admin frontend, and continue to maintain and operate it. This gives me experience not only building software, but also running a real online business where reliability, payments and operational workflows matter. How I work: I clarify the problem before writing code, give realistic estimates, and deliver maintainable, tested work with clear documentation. I am comfortable taking ownership of an existing codebase as well as building new systems from scratch. Send me a short description of what you're trying to build or fix. I'll tell you whether it's a good match for my experience and how I would approach it.