Alexander S.

I build and maintain complex backend systems: a domain-oriented architecture on a custom application core, with one typed data model and one main write path. Changes get transactions, an audit trail, and live updates, with row-level locks where concurrent operations need them. My main project is a large production platform that I have developed and supported for several years as its main developer. It connects production machines, smart storage racks, barcode and QR scanners, and business systems in real time: machine events, material tracking, and operator guidance, from the shop floor to AWS. The code is organized by business domain, with services and typed DTOs: about 390,000 lines of Python and 770+ test files. I have also built and maintained a multi-source data platform, including database design and data normalization. What I can do for you: - Connect production equipment, scanners, and internal systems to one platform, with real-time events and reliable data exchange - Build a custom internal system or backend from scratch - Audit an existing codebase, then refactor it step by step around clear domain boundaries, without stopping the product - Connect your systems through APIs - Set up AWS infrastructure with Terraform and CI/CD My stack: Python, Django, PostgreSQL, Redis, Dramatiq, Celery, Pydantic, HTMX, Vue.js, WebSockets, Docker, AWS ECS, Terraform. How I work: I prefer fixed-price projects with clear milestones. For existing code, the first milestone is a paid audit, so the scope and the price of further work are based on the real code, not on guesses. I use AI coding tools such as Claude Code, and I review and test everything I deliver. I have completed 36 jobs on Upwork since 2016. I prefer written communication.