Oscar Cuéllar

Hi, I am Oscar

+7 years of experience. I have a bachelor's degree in Science and Systems Engineering. Currently I live in Winnipeg, Manitoba. FullStack Web Developer.

Experience

  1. React Senior Developer and Team Leader. Current

    Intuitiva S.A. - Guatemala, Guatemala. (Remotely).

    Top Guatemala Company providing ERP & CRM and custom software services. 10 employees. 2000 active users per day. 500 request per minute to the systems.

    Led development and maintenance of ZAURU, an enterprise ERP serving 2,000+ daily active users at 500+ requests per minute, using React with Redux and Redux Toolkit for client state.

    Managed and mentored a development team building custom web applications on the ERP & CRM APIs.

    Set up and operate a Hasura GraphQL service over the company ERP so associated web applications can query and create data against the core system.

    Designed and delivered 6 full e-commerce sites on Webstudio, integrated with a fully customized and extended Payload CMS and CRM APIs, using Payload CMS GraphQL to query and create content and data.

    Built and maintained AWS infrastructure: ECS containers, SQS job and email queues, RDS databases, Lightsail for open-source services, plus Lambda and S3.

    Stood up Prometheus and Grafana for production monitoring, with dashboards for application health, infrastructure metrics, and operational KPIs.

    Own day-to-day CI/CD for web applications with GitHub Actions, from build and test through production deploy.

    Architected offline-first web applications with Electric SQL and TanStack DB that stay fully usable without internet.

    Adopted and integrated React Router (framework mode), shadcn/ui, TanStack Query, and TanStack DB across new and existing projects.

    Ran client-facing requirements sessions with diverse stakeholder profiles, with emotional intelligence and professional composure.

    Designed the team's isolated AI-agent delivery workflow: sandboxed GitHub branches, layered tests, then AI and human PR review, so shared staging and production stay untouched until merge.

    AI Highlight: Built a Model Context Protocol (MCP) server for ZAURU so the ERP chatbot can find documents from incomplete questions (customer, date, amount) through staged tool calls, then explain why a record is missing and link to it. The model chooses the investigation; the backend enforces RLS and per-user permissions. Read-only today, with simple mutations planned for non-sensitive data.

    AI Highlight: Integrated Google's gemma_q4f16_embedding model to embed all ERP items; built a search API that vectorizes queries at runtime, scores similarity against those vectors, and enables semantic fuzzy search across online stores beyond exact keywords.

    AI Highlight: Designed an isolated, human-in-the-loop delivery pipeline for coding agents using Cursor, GitHub Copilot, OpenCode, and a self-hosted Ollama server running Qwen. Each agent works in its own sandbox and GitHub branch, runs layered tests against existing features in a disposable environment that never touches shared staging or production, then opens a pull request reviewed first by an AI code-review agent and then by a human. Agent PRs arrive already tested and reviewed.

  2. Part-time Instructor, Full Stack Web Development Department.

    Red River College - Winnipeg, Manitoba

    Red River College (RRC) is a leading institution in Manitoba, Canada, offering comprehensive educational programs designed to provide students with hands-on, practical skills. The Full Stack Web Development program equips students with the expertise to design, develop, and deploy dynamic web applications.

    WEBD-3010 - Web Development 3: REST Python APIs, CI/CD pipelines, and cloud infrastructure. Students built full web applications with Python frameworks.

    WEBD-3012 - Business Systems Build and Testing: Deployment strategies, QA, testing methodologies, and best practices, culminating in a portfolio website launch.

    WEBD-2010 - Project Management & Agile Business Analysis: Project management fundamentals, agile methods, stakeholder collaboration, and delivering business value.

  3. Full Stack Developer.

    Public Ministry of Guatemala. - Guatemala, Guatemala. (In person).

    Branch of the Government dedicated to ensuring compliance with justice in the country. Approx. 70 Tech employees. 1500 active users per day on the platforms.

    Built ASTREA, the main national platform prosecutors use to manage complaints across Guatemala, used by about 1,500 people a day. Security and privacy were first-order concerns because the system holds sensitive data on the Guatemalan population.

    Connected ASTREA to government entities including RENAP (National Registry of Persons), SIB (Superintendence of Banks), IGSS, and others, so prosecutors could query identity, banking, and social-security records from inside the case file.

    Led and trained development teams on ASTREA and AyudaGT.

    Designed intuitive interfaces including an interactive Timeline visualizing complete criminal histories, using React with Material UI (MUI), Redux and Redux Toolkit for client state.

    Implemented AWS SQS asynchronous messaging for email and high-concurrency workloads, and operated AWS RDS and Lightsail for production justice applications.

    Conducted requirements gathering sessions directly with MP stakeholders and end-users to ensure developed features met operational needs.

Skills

Frontend
Advanced
Tailwind CSS
HTML
CSS
JavaScript
TypeScript
React
React Router
Remix
Gatsby
Redux
Material UI
shadcn/ui
TanStack Query
TanStack DB
Intermediate
Astro
Next.js
Bootstrap
Flowbite
Learning
Angular
Backend
Advanced
NodeJS
ExpressJS
NestJS
.NET Framework
JavaScript
TypeScript
C#
Intermediate
Python
Java
Learning
Ruby
AI
Advanced
LLMs
AI agents
MCP
Cursor
GitHub Copilot
OpenCode
Ollama
Qwen
DataBases
Software

About Me

My name is Oscar René, but everyone calls me Koka. I'm passionate about web development & Teaching. I taught WEBD-3012, WEBD-3010 and WEBD-2010 at Red River College (Winnipeg, Manitoba) as a part-time instructor from May 2024 to June 2025.

Some of my successes include the creation of ASTREA and AYUDA.GT, two systems used nationally in Guatemala for reporting and assisting victims, in collaboration with Justice Education Society and the Public Ministry of Guatemala.

Oscar Cuéllar