I’m a backend-focused full-stack developer and automation specialist based in Romania. Over 15 years running my own production platform, I have hands-on experience with encrypted user datasets, credit/balance logic, semi-automated verification flows and constant security hardening in high-risk environments. I build end-to-end systems: secure REST APIs, data processing pipelines, automation tools, and containerized services. I work across the stack—from Python backends (Django REST Framework, FastAPI) and Docker-based deployments to Vue 3 and Next.js frontends—prioritizing practical, resilient architectures and production-ready workflows. I can operate across the entire stack and take ownership from infrastructure setup to frontend interfaces.
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This project is a pure backend prototype built with Kotlin and Spring Boot.
Its purpose is to demonstrate how a production-style backend can orchestrate external data sources, apply business logic, and expose a clean REST API — without UI, database, or infrastructure overhead.
The system estimates the potential increase in house value after installing a heat pump, based on official address resolution and energy label interpretation.
Key Capabilities
Clean REST endpoint: /api/value-impact
Real integration with BAG (PDOK) for address resolution
Controlled mock fallbacks for restricted APIs (WOZ, Energy Label)
Deterministic calculation logic with clear responsibility boundaries
Layered Spring Boot architecture (controller / service / client / calculator)
Tech Stack
Kotlin
Java 17
Spring Boot 3.x
Gradle (Kotlin DSL)
REST API
What This Demo Demonstrates
Backend system design and responsibility separation
Safe handling of unavailable or restricted external APIs
Clear orchestration of multiple data sources
Readable, maintainable Spring Boot structure
Production-oriented thinking without unnecessary complexity
This demo intentionally excludes:
Database persistence
Authentication
UI or frontend
Real partner dispatching
The focus is backend architecture and correctness, not feature volume.
🔗 Source code:
https://www.twine.net/signin
Important note (for reviewers)
Replacing the mock clients with real WOZ / EnergyLabel integrations requires minimal changes, as the interfaces and flow are already defined.
Author: Andrei Sorin Ștefan
I designed and implemented a backend-focused prototype to demonstrate a configuration-driven lead routing and recommendation engine.
The goal was not UI polish or production deployment, but to validate architecture, flexibility, and scalability early.
The system uses a Spring Boot + Kotlin backend with a lightweight Vue 3 frontend consuming a clean REST API.
All business logic (questions, scoring, partner eligibility) is JSON-configured, enabling updates without code changes.
Key Highlights
Dynamic questionnaire (no hardcoded UI logic)
Config-driven scoring & partner eligibility
Deterministic lead routing & recommendations
Clean REST API design
Lead history logging for QA and testing
Zero-deployment updates (JSON → restart)
Tech Stack
Backend: Kotlin, Java 17, Spring Boot, REST, UUID
Frontend: Vue 3, Composition API, TailwindCSS
Storage (demo): Local JSON (config + lead history)
What This Demo Shows
How I structure backend systems
How I design for change, not one-off logic
Ability to adapt quickly to a new stack (Kotlin)
Readiness to evolve this into a real production system
Demo video:
Source code:
https://github.com/PhoenixZuko/lead-routing-demo
I designed and implemented a fully local automation and analytics platform for monitoring automotive marketplaces (Facebook Marketplace, Craigslist) under strict client constraints.
The system operates entirely on the user’s machine with no cloud services, no external APIs, and full execution transparency. Automation is browser-based, real-time, and intentionally non-aggressive, mimicking human interaction to reduce platform risk.
Key features include a controlled ETL pipeline, keyword-based listing analysis, duplicate detection, persistent browser sessions, and an interactive local dashboard for filtering and decision support. The solution was built to coexist safely with other business applications and to run reliably over long periods.
Links
Source code (GitHub):
https://github.com/PhoenixZuko/AutoMarketFlow-Car-Market-Scraper-Interactive-Dashboard
Demo video:
Source code (GitHub):
https://github.com/PhoenixZuko/pricing-intelligence-platformDemo video (YouTube):
I designed and implemented a production-grade pricing intelligence platform focused on long-term stability, low operational risk, and minimal infrastructure overhead.
The system performs scheduled browser-based data extraction, normalization, classification, and storage, running fully self-contained on a lightweight Alpine Linux environment. All business logic (types, categories, subcategories, schedules) is YAML-driven, allowing safe updates without code changes or redeployments.
The architecture prioritizes predictable behavior, controlled crawl frequency, and full observability, avoiding aggressive scraping patterns or cloud dependencies. Data is stored in PostgreSQL and exposed through a secured API and Metabase dashboards for analytics.
This project was built to operate reliably over time, not as a one-off scraper, and reflects a strong focus on maintainability, extensibility, and production safety.
Links
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