Python backend engineer building APIs with FastAPI, PostgreSQL and Docker, with security designed in from the start rather than added at the end.

Before moving into engineering, I spent more than a decade in international business development and financial risk intelligence, including roles at the Polish Embassy in Brazil and Refinitiv / World-Check. That background still shapes how I work: I care about systems that are reliable, auditable and useful under real-world constraints, and I'm comfortable in enterprise and compliance-heavy environments.

A FastAPI + PostgreSQL service, containerized and hardened, with a security pipeline built into CI (pytest, Hadolint, Gitleaks, Semgrep, Trivy).

I deliberately introduce realistic vulnerabilities (SQL injection, broken JWT validation, IDOR, mass assignment), then exploit, detect, fix and regression-test each one. The write-ups document what automated scanners catch and, more importantly, what they miss.

In progress: v1.0 due November 2026.

• API design with FastAPI: Pydantic validation, JWT/OAuth authentication patterns, pagination and filtering, background tasks
• Data: PostgreSQL with SQLAlchemy and Alembic; Redis for caching and rate limiting
• Containers: multi-stage Docker builds, Compose, networking, health checks and file-based secrets
• Performance: async patterns, bottleneck analysis and debugging under load
• Security in delivery: CI scanning, threat modelling and secure configuration

A privacy-focused service for sending sensitive files securely. It explores encryption-aware design and privacy-first architecture while keeping the experience simple.

A map-based tool for finding football stadiums nearby and planning football trips. It explores geospatial data, location-aware interfaces and incremental platform growth, with the goal of deep coverage across leagues and countries.

A lightweight weather analytics tool that tracks conditions across selected cities. It explores API integration, backend data collection and simple visualization on minimal cloud infrastructure.

• Backend: Python · FastAPI · Pydantic · SQLAlchemy · Alembic · pytest
• Data: PostgreSQL · Redis · SQL
• Infrastructure: Docker · Docker Compose · Nginx · Linux · Bash · GitHub Actions
• Cloud: Azure · Bicep
• Also: JavaScript · PowerShell · HTML/CSS

Polish (native) · English, Portuguese, Russian (fluent) · Spanish, German (advanced) · Dutch (basic)

• LinkedIn: marek-zarzycki
• Blog: dev.to/marcoz
• Website: nubecode.eu