Yilmar – Python, React, PostgreSQL, experts in Lemon.io

Yilmar

From Colombia (UTC-5)flag

Full-stack Web Developer|Senior
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Yilmar – Python, React, PostgreSQL

Yilmar is a senior full-stack developer with 8 years of experience, specializing in building scalable web applications, backend systems, and AI-integrated solutions. He has demonstrated strong production ownership, particularly in developing reliable systems and working with complex technical requirements under real-world constraints. He brings a structured approach to problem-solving, clear communication, adaptability, and a strong focus on delivering solutions that meet client and business needs.

8 years of commercial experience in
AI
Analytics
Architecture
Healthcare
Productivity
Social impact
Collaboration tools
Enterprise software
Mobile apps
SaaS
Web development
Main technologies
Python
7 years
React
7 years
PostgreSQL
2 years
FastAPI
4 years
MongoDB
2 years
Additional skills
AWS
Typescript
React Native
Django
Figma
MySQL
JavaScript
LangChain
LangGraph
Docker
Azure DevOps
Next.js
Direct hire
Possible
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Experience Highlights

Senior AI Full-stack Developer
Oct 2024 - Ongoing1 year 11 months
Project Overview

An intelligent dynamic reporting platform that automates project governance and progress tracking across multiple organizational initiatives. The system leverages an autonomous SQL agent to query, aggregate, and analyze multi-source project metrics, generating customizable data visualizations, structured tables, and executive summaries that users can refine via interactive chat before exporting to production-grade PDF and PowerPoint decks.

Responsibilities:
  • Architected and implemented the end-to-end full-stack platform using FastAPI, Python, React, and TypeScript, delivering a high-throughput reporting engine.
  • Designed a LangChain-powered SQL agent capable of dynamically inspecting schema definitions, synthesizing optimized read queries, and aggregating project metrics with strict read-only execution sandboxing.
  • Built dynamic chart- and table-generation pipelines, allowing users to customize, edit, or regenerate specific report sections via natural language commands and real-time UI controls.
  • Engineered backend export workers capable of rendering complex document templates into high-fidelity PDF reports and interactive PowerPoint presentations asynchronously.
  • Implemented structured error handling, schema validation using Pydantic, and comprehensive API caching to maintain sub-second response times across heavy analytical queries.
  • Containerized all application services using Docker and configured CI/CD delivery pipelines via GitHub Actions targeting AWS infrastructure (ECS Fargate, Aurora PostgreSQL, S3).
Project Tech stack:
Python
FastAPI
React
Typescript
LangChain
LangGraph
PostgreSQL
Vector Databases
GitHub Actions
AWS
Pydantic
AI-assisted coding
Claude Code
AI agent orchestration
Senior AI Full-stack Developer
Dec 2023 - Sep 20249 months
Project Overview

A mission-critical mobile application and conversational AI assistant designed for field promoters and community coordinators. The solution resolves operational data bottlenecks by providing an intuitive, voice- and text-enabled Retrieval-Augmented Generation (RAG) interface, enabling field staff with diverse digital literacy levels to instantly query demographic records, family profiles, and assigned social welfare benefits in real time.

Responsibilities:
  • Engineered the cross-platform mobile client with React Native and TypeScript, prioritizing accessibility, minimal network latency, and offline-resilient local caching.
  • Architected a robust RAG backend in FastAPI utilizing PostgreSQL/PGVector for semantic search over structured demographic data, sensitive family records, and program guidelines.
  • Implemented strict role-based data isolation and HIPAA/data-privacy safeguards, ensuring context retrieval is strictly constrained to authorized field personnel.
  • Optimized vector similarity search latency by applying hybrid search strategies (dense embeddings + sparse keyword matching) and pre-filtering metadata before vector distance calculations.
  • Built standardized REST endpoints for conversational streaming responses, managing token utilization and session history across asynchronous background workers.
  • Deployed containerized backend services to AWS ECS Fargate, configuring automated horizontal scaling policies based on operational peak hours.
Project Tech stack:
Python
FastAPI
React Native
Typescript
PostgreSQL
Vector Databases
LangChain
AWS
Docker
Redis
Pydantic
API
OpenAI API
Full-stack Developer
Nov 2022 - Nov 20231 year
Project Overview

A comprehensive document management and real-time collaboration module integrated into an enterprise CRM/CHT ecosystem. The system streamlines end-to-end document lifecycles for heterogeneous file types (PDF, Office, rich media, and audio), featuring in-browser PDF annotation with drag-and-drop workflows, multi-party electronic signature validation, role-based access control (RBAC), and bi-directional integration with Microsoft SharePoint.

Project gallery:
Portfolio example for El Sol Neighborhood Educational Center - Under NDA by Yilmar, Full-Stack Developer
Portfolio example for El Sol Neighborhood Educational Center - Under NDA by Yilmar, Full-Stack Developer
Portfolio example for El Sol Neighborhood Educational Center - Under NDA by Yilmar, Full-Stack Developer
Responsibilities:
  • Led the full-stack engineering of the core document repository module using React, TypeScript, and Python/FastAPI microservices;
  • Built an interactive PDF workspace supporting drag-and-drop placement, visual in-line annotations, highlight persistence, and digital signature placement directly in the browser;
  • Integrated Microsoft Graph APIs for automated synchronization, permissions management, and seamless check-in/check-out of Office files stored in SharePoint;
  • Designed a granular role-based access control (RBAC) matrix governing view, edit, download, and audit-log permissions across collaborative workspaces;
  • Implemented secure file streaming, chunked uploads, and asynchronous virus scanning pipelines for large file formats leveraging AWS S3 pre-signed URLs;
  • Maintained 99.9% uptime by containerizing microservices with Docker and integrating structured audit logs for compliance tracking.
Project Tech stack:
Python
FastAPI
Typescript
React
PostgreSQL
AWS
Docker
Tailwind CSS
Jest
AWS Lambda
pytest
Full-stack Developer
Feb 2022 - Oct 20228 months
Project Overview

A flexible dynamic form engine and data collection platform capable of creating, versioning, and deploying complex multi-page surveys across various CRM modules. The engine supports over 25 customizable question types — including matrix grids, voice recordings, geolocation, conditional branching logic, and electronic signatures — handling high-variability submission payloads with rapid retrieval performance.

Project gallery:
Portfolio example for El Sol Neighborhood Educational Center - Under NDA by Yilmar, Full-Stack Developer
Portfolio example for El Sol Neighborhood Educational Center - Under NDA by Yilmar, Full-Stack Developer
Responsibilities:
  • Designed the full-stack architecture with React/TypeScript for the interactive drag-and-drop builder and Python/FastAPI for execution and submission processing;
  • Selected and implemented MongoDB for form definition and submission storage to effectively accommodate extreme schema polymorphism, deeply nested survey structures, and evolving field definitions without schema migration bottlenecks;
  • Built dynamic client-side and server-side validation engines that evaluate runtime conditional logic, dependent question visibility, and multi-step validation rules;
  • Engineered media capture and storage handlers for rich input types (voice recordings, canvas-based signature vectors, file attachments) uploaded directly to object storage;
  • Implemented high-performance aggregation pipelines in MongoDB to enable real-time survey response analytics, filtering, and automated CSV/XLSX export routines;
  • Conducted load testing and optimized query indexes to ensure seamless data ingestion during high-concurrency survey rollout campaigns.
Project Tech stack:
Python
FastAPI
React
Typescript
MongoDB
AWS
Docker
GitHub Actions
Tailwind CSS
Pydantic
pytest

Education

2018
Computer Software Engineering
Bachelor’s Degree in Software Engineering

Languages

Spanish
Advanced
English
Advanced

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