Marcos Villalba

Senior Software Engineer

Paraguay (UTC -3)

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 AI-powered SaaS products using Agentic LLM workflows. GCP Certified with deep expertise across the .NET stack, React, Python, and cloud-native infrastructure.

Work Experience

Senior .NET Developer
Kubikware
July 2025 - Present

Remote (US). Working with React, .NET 9, and Azure.

Key Highlights:

  • 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.
React.NET 9AzureDatabricksRedux Saga
Team Lead & Senior .NET Developer
Forty AU
January 2024 - July 2025

Remote (US). Promoted to Team Lead in 8 months, leading a 6-person cross-functional team.

Key Highlights:

  • 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.
React PWA.NETDjangoPythonReact NativeAWSGCPTerraformStripe
Lead Engineer & Architect
Election Statistics Platform (Concertación)
December 2022 - April 2023

Part-Time Contractor. Led emergency recovery of national election platform during live vote counting.

Key Highlights:

  • 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.
.NET 6ReactFirebaseAzureMobile AppAnalytics
Technical Lead & PM
Creadores
April 2021 - December 2023

Shipped 6+ production products including real-time Grocery Delivery and Cattle Auction platform. Dual-hatted as PM (2022+) managing stakeholders.

Key Highlights:

  • Developed Flutter mobile app with WebSockets for real-time updates.
  • Built e-commerce API in .NET 6 with C#.
  • Managed client stakeholders while maintaining hands-on ownership of critical backend features.
C#.NET 6FlutterBlazorWebSockets

Freelance Consultancy Work

AI Hotel Concierge (SaaS Prototype)
January 2026

Agentic workflows using Gemini Function Calling to autonomously query databases and confirm bookings via WhatsApp.

Highlights:

  • Architected a multi-tenant system that ensures strict data isolation and custom prompt contexts for each hotel client.
  • Engineered agentic workflows using Gemini Function Calling.
AstroReactGeminiCloudflareWhatsApp API
Mente Imparable (GenAI PWA)
July 2025 - December 2025

Offline-first meditation app with personalized audio generation using Google Chirp.

Highlights:

  • 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.
Astro SSRGoogle Chirp TTSFirebase

Skills & Technologies

Backend
C#.NET 9Entity Framework CoreDjangoPython
Frontend
ReactTypeScriptAstroNext.jsBlazorReact NativeFlutter
Cloud & DevOps
GCP (Certified)AWSAzureDockerTerraform
Applied AI
LLM Integration (Gemini)Function CallingDynamic Context InjectionMulti-Modal Pipelines
Data
PostgreSQLDatabricksFirebase

Career Timeline

2026

AI Hotel Concierge (SaaS Prototype)

Client Project

January 2026Freelance

2025

Senior .NET Developer

Kubikware

July 2025 - PresentWork

Mente Imparable (GenAI PWA)

Client Project

July 2025 - December 2025Freelance

2024

Team Lead & Senior .NET Developer

Forty AU

January 2024 - July 2025Work

2022

Lead Engineer & Architect

Election Statistics Platform (Concertación)

December 2022 - April 2023Work

2021

Technical Lead & PM

Creadores

April 2021 - December 2023Work