Rubén D. Guerrero N. | Backend Developer

About Me

I am a backend developer passionate about scalable architecture, distributed systems, and Clean Architecture. My philosophy is that writing code is the means, but building maintainable and resilient systems is the true art.

As a Vendure Core Contributor (the #1 headless e-commerce framework in NestJS), my contributions impact a global community of over 10,000 developers. I specialize in solving complex performance issues, SQL query optimization, and high-traffic API design.

My approach combines traditional backend robustness with Generative AI innovation, applying advanced prompt engineering to integrate language models into critical business processes.

Open Source & Experience

Present

Vendure Core Contributor

High-traffic system optimization and service architecture in NestJS.

SQL: N+1 query elimination via In operator batch loading (Issue #4387).
Architecture: Designed getProductVariantsForCollections for efficient transactions.
DevOps: Monorepo conflict resolution (20+ files) and dependency standardization.
Tooling: Modernization of internal automation scripts for Windows environments.
View more PRs on GitHub

Tech Stack

JavaScript

Node.js

TypeScript

NestJS

PostgreSQL

AI / LLMs

n8n / Low-Code

Docker

Git

Featured Projects

Vendure Core Contribution (Open Source/Fork)

Optimized core performance by designing batch loading architectures and resolving critical bottlenecks in data filtering.

SQL Optimization: Eliminated N+1 queries (Issue #4387) using batch loading with TypeORM's In operator.
Architecture: Implemented getProductVariantsForCollections for efficient atomic transactions.
DevOps/Tooling: Monorepo synchronization (20+ files) and Node.js script modernization for Windows.

Solving complex problems at the heart of modern e-commerce. 📉⚡

TypeORM SQL Optimization Monorepo (Lerna) Node.js Modernization

CCSC Bot - Clinical Center Madrid

Intelligent virtual assistant for Clinical Center Madrid. Centralizes information for 43 specialists across 35 specialties via a conversational Telegram interface.

Innovation: Implemented fuzzy search for names/specialties and a resilient fallback system using Mistral AI for natural language queries outside the local database.

n8n Mistral AI Web Scraping Telegram API

Sustainable Credits Indexer

High-performance backend service indexing over 1 million off-chain events from ERC-1155 (RWA) contracts. Reduces data access time by 95% through an optimized RESTful API and atomic persistence.

NestJS PostgreSQL Blockchain

Bullfighting AI Bot

AI Chatbot (Gemini API) and NestJS. As a Prompt Engineer, I achieved 85% natural language query processing, providing real-time event info via automated web scraping (Puppeteer/Cheerio).

NestJS Gemini AI Scraping

Medical Appointments API

Robust clinic management API handling 3000+ monthly appointments. Implements granular roles, medical history in JSONB, and cloud-based prescription uploads with high security standards.

NestJS TypeORM Security

Bowling Tournament Management

Web platform for bowling tournament management with automatic bracket generation and real-time score tracking for competitive leagues.

NestJS PostgreSQL Logic

Shopping Cart System

E-commerce engine focused on transactional integrity for carts, concurrent inventory management, and scalable order flows.

Node.js NestJS PostgreSQL

Amusement Park API

RESTful API for theme park administration, managing ticket sales, attraction access, and administrative staff roles.

NestJS TypeORM Architecture

Medical AI Bot (@CitasMedicbot)

Patient conversational interface. Manages appointments, locates pharmacies via GPS, and generates emergency QR codes with vital first-aid data.

Telegram API Generative AI Geo & QR

Let's Talk!

I am always open to discussing new projects, creative ideas, or opportunities to be part of your visions.

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