MARCOS VILLALBA

Senior Software Engineer Paraguay (UTC -3) | +595 984 104 237 marcosariel.villalba@gmail.com | LinkedIn

PROFESSIONAL SUMMARY

Senior Engineer with 5+ years of experience leading teams and shipping production systems at scale. Architected a national election platform processing 1.3M+ events under live conditions. Currently building an AI powered compliance verification platform with hybrid RAG and agentic tool use loops. GCP Certified with deep expertise across .NET, React, Python, and cloud native infrastructure.

TECHNICAL SKILLS

• Backend: C#, .NET 9, Entity Framework Core, Django, Python
• Frontend: React, TypeScript, Astro, Next.js, Blazor, React Native, Flutter
• Cloud & DevOps: GCP (Certified), AWS, Azure, Docker, Terraform, Railway
• Applied AI: RAG (Hybrid Search, Cross-Encoder Reranking), Agentic Tool Use, Multi Model Routing, Function Calling
• Data: PostgreSQL, pgvector, Supabase, Databricks, Firebase

PROFESSIONAL EXPERIENCE

Senior .NET Developer

Kubikware | Remote (US) July 2025 - Present

• Stack: React, .NET 9, Azure
• Cut login latency by 60% by refactoring legacy Redux Saga authentication to Context API + Azure B2C.
• Accelerated roadmap by 1 month by building a strongly-typed Databricks query engine with automated serialization, simplifying query code and improving maintainability.

Team Lead & Senior .NET Developer

Forty AU | Remote (US) January 2024 - July 2025

• Stack: React PWA, .NET, Django, Python, React Native
• Promoted to Team Lead in 8 months (first Paraguayan office developer to achieve this), leading a 6-person cross-functional team (Dev + QA).
• Architected a high-concurrency Web Push Notification engine using .NET Hosted Services, integrating AWS EventBridge Scheduler to handle precise, timezone-aware delivery for 350+ hospital partners.
• Ensured the stability and reliability of a $1M+/month payment pipeline integrating Stripe, Dwolla, and PandaDoc in Django.
• Managed production infrastructure via Terraform on GCP.
• Established engineering standards for React PWA + .NET Backend, improving code consistency and review efficiency across the team.

Lead Engineer & Architect

Election Statistics Platform (Concertación) | Part-Time Contractor December 2022 - April 2023

• Stack: .NET 6, React, Firebase, Azure
• Led emergency recovery of national election platform during live vote counting. Redesigned failing single-worker architecture to distributed micro-batching system (18 workers, 1K event batches) in 20 minutes, ensuring complete data capture across 1.3M+ events.
• Built sub-second fuzzy search across 4.7M voter records using Levenshtein Distance + Span memory optimization.
• Delivered end-to-end Mobile App, Backend API, and Analytics Dashboard in 4 months under strict election deadlines.

Technical Lead & PM

Creadores April 2021 - December 2023

• Stack: C#, .NET 6, Flutter, Blazor
• Shipped 6+ production products including real-time Grocery Delivery (Flutter/WebSockets) and Cattle Auction platform (Blazor/.NET).
• Dual-hatted as PM (2022+): Managed client stakeholders while maintaining hands-on ownership of critical backend features.

PROJECTS (AI & SAAS)

Engineering Intelligence SaaS (Compliance Verification Platform) February 2026 - Present | Stack: FastAPI, React 19, Supabase (pgvector), Gemini/Gemma/Mistral, Railway

• Built a hybrid RAG pipeline (dense + sparse + RRF fusion + ZeroEntropy cross-encoder reranking) with multilingual query translation across English, Spanish, and Portuguese.
• Engineered a ReAct agentic tool use loop with 5 domain specific tools (Sympy formula engine, CPM scheduler, XLSX cell-level access), budget management, and live progress streaming.
• Designed a recursive compliance architecture with multilingual translation (Gemma), parallel investigator spawning, and a multi-stage feedback loop (decompose → DeepSeek per-claim validation → synthesizer retry → coherence review).

Mente Imparable (GenAI PWA) July 2025 - December 2025 | Stack: Astro SSR, Google Chirp TTS, Firebase

• Built an offline-first meditation app with personalized audio generation using Google Chirp.
• Engineered a Dynamic Context Pipeline to inject user goals and versioned "Brain" prompts via feature flags.

EDUCATION & CERTIFICATIONS

• Professional Cloud Architect - Google Cloud Platform (2025)
• Mechatronics Engineer - Facultad de Ingeniería de la Universidad Nacional de Asunción (2021)

LANGUAGES

• English: Fluent
• Spanish: Native