Marcos Villalba

Senior Software Engineer | .NET / Backend / Cloud

Paraguay (UTC -3)

Senior software engineer and Google Cloud Professional Cloud Architect with 5+ years building production .NET/backend and cloud systems, including US consultancy work since January 2024. Led a 6-person team at FortyAU, delivered notification infrastructure for 350+ partner organizations, and stabilized the Concertación Nacional election-results platform that processed 1.3M+ vote updates.

Work Experience

Senior .NET Developer
Kubikware
July 2025 - Present

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

Key Highlights:

  • Migrated authentication to Azure B2C with custom policies and streamlined the client authentication flow.
  • Made cross-system event ingestion idempotent by deriving internal UUIDv8 IDs from stable federated IDs, so duplicate and out-of-order create events upsert to the same mapped entity.
  • Built a strongly typed .NET query builder over the Databricks SQL API, reducing query-construction errors for analytics features.
.NETReactAzureDatabricks
Team Lead & Senior .NET Developer
FortyAU
January 2024 - July 2025

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

Key Highlights:

  • Promoted to Team Lead after 8 months; led a 6-person cross-functional team and owned product scope, releases, acceptance criteria, sprint priorities, and direct client communication.
  • Built a .NET background task runner with bounded concurrency, a backpressure queue, and graceful shutdown for time zone-aware notification delivery to 350+ partner organizations.
  • Built a Terraform-managed GCP email pipeline (Cloud Scheduler to Cloud Tasks) to generate PandaDoc contracts asynchronously; supported Dwolla payment ledger reconciliation workflows.
.NETDjangoPythonReact PWAAWSGCPTerraformCloud TasksPandaDocStripe
Full-Stack Engineer
Concertación Nacional (Paraguay) - Election Results Platform
December 2022 - April 2023

Direct part-time contract. Stabilized a national election-results platform during live vote counting.

Key Highlights:

  • Partitioned a failing single-worker sync into 18 department-specific workers, processing 1.3M+ vote updates.
  • Built fuzzy-matching utilities using Levenshtein distance and name-token scoring to query and validate voter records.
  • Owned the four-month backend API and analytics dashboard build end to end as the sole engineer under election deadlines.
.NETBlazor WebAssemblyFirebaseAzureGCPAnalytics
Technical Lead & Full-Stack Developer
Creadores
April 2021 - December 2023

Joined as a developer and was promoted into technical leadership in 2022. Shipped 6+ production products including a real-time grocery delivery app and cattle auction platform.

Key Highlights:

  • Owned client discovery, scope, and end-to-end delivery while staying hands-on across backend features.
  • Led delivery of a real-time grocery delivery app (Flutter, WebSockets) and a cattle auction platform (Blazor/.NET) through launch.
  • Translated client needs into shipped web and mobile software across 6+ custom products.
C#.NETFlutterBlazorWebSockets

Freelance Consultancy Work

Independent prototype that explores turning unstructured project documents and format exemplars into reviewable spreadsheets and reports with formula traces and source links.

Highlights:

  • Prototyped a hybrid RAG pipeline (dense/sparse search + reranking) supporting multilingual query translation for engineering project documents.
  • Built an experimental workflow for compiling unstructured documents into reviewable spreadsheets and reports with automated formula tracing and source citations.
  • Designed a prototype document ingestion service (FastAPI + Cloudflare R2) featuring an automated GPU-based OCR pipeline on Modal for scanned files.
C#.NET 10FastAPIReact 19PostgrespgvectorCloudflare R2ModalRailway
Mente Imparable (GenAI PWA Prototype)
July 2025 - December 2025

Personal prototype for an offline-first meditation app with personalized audio generation using Google Gemini.

Highlights:

  • Prototyped an offline-first meditation app with personalized audio generation using Google Gemini.
  • Engineered a Dynamic Context Pipeline to inject user goals and versioned 'Brain' prompts via feature flags.
Astro SSRGoogle Gemini (Voice)Firebase

Skills & Technologies

Backend
C#.NET 9/10ASP.NET CoreEntity Framework CoreREST APIsAuthentication FlowsPythonFastAPIDjango
Frontend
ReactTypeScriptAstroNext.jsBlazorReact NativeFlutter
Cloud & Tools
GCP (Certified)AWSAzureDockerTerraformCI/CDGitClaude CodeCodex
Data
SQLPostgreSQLpgvectorSupabaseDatabricksFirebase

Career Timeline

2026

Engineering Intelligence (Solo AI Prototype)

Client Project

February 2026 - PresentFreelance

2025

Senior .NET Developer

Kubikware

July 2025 - PresentWork

Mente Imparable (GenAI PWA Prototype)

Client Project

July 2025 - December 2025Freelance

2024

Team Lead & Senior .NET Developer

FortyAU

January 2024 - July 2025Work

2022

Full-Stack Engineer

Concertación Nacional (Paraguay) - Election Results Platform

December 2022 - April 2023Work

2021

Technical Lead & Full-Stack Developer

Creadores

April 2021 - December 2023Work