Open to opportunities

Emerson Cardona

@emersoncardona

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Senior full-stack engineer building cloud web platforms with REST APIs, reactive UIs, and measurable cost wins.

Guatemala

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What I'm looking for

I’m looking for a cloud-focused role where I can own full-stack delivery, design RESTful APIs, and harden systems with Zero Trust. I want teams that value measurable performance, clean architecture, and continuous improvement.

I’m a Senior Full Stack Software Engineer with 6+ years building and deploying web platforms on cloud infrastructure. I bring strong end-to-end ownership—from requirements gathering and technical modeling to production deployment—with a continuous improvement mindset.

At GSI Guatemala, I integrated LLM APIs (Claude and ChatGPT) into production systems, using TOON (Token-Oriented Object Notation) to reduce token consumption by up to 60% versus JSON and significantly cut inference costs. I design and implement high-performance RESTful APIs for multi-tenant SaaS on AWS, and I apply Zero Trust principles to secure inter-service communication with least-privilege access.

I’ve led development and launch of a regional banking web platform, aligning technical requirements with stakeholder expectations and delivering on schedule. I also implemented vendor payment integrations by generating ISO 20022 PAIN files and securely transferring them via FTPS, ensuring traceability, integrity, and regulatory compliance.

I stabilize delivery by introducing Scrum and structured code reviews, improving predictability and reducing production defects. From FastAPI/React/Vue microservices to query optimization on PostgreSQL, I focus on performance, reliability, and maintainability—backed by architecture decisions documented through ADRs and consistent coding standards.

Experience

Work history, roles, and key accomplishments

Current

Full Stack Software Architect

Current

GSI Guatemala

Feb 2025 - Present (1 year 4 months)

Integrated Claude/ChatGPT LLM APIs using TOON serialization, reducing token consumption by up to 60% and significantly cutting inference costs. Designed RESTful APIs for a multi-tenant AWS SaaS, applied Zero Trust least-privilege security, optimized PostgreSQL schemas for critical load, and led a regional banking platform launch plus ISO 20022 PAIN payment integration via FTPS.

ChatGpt TOON Serialization RESTful APIs Microservices FTP

Full Stack Team Lead

GSI Guatemala

Mar 2024 - Feb 2025 (11 months)

Built full-stack SaaS features with Python (FastAPI) and React/Vue.js while maintaining strong unit test coverage and CI/CD pipelines. Reduced REST API latency by over 60%, led AWS microservices (Lambda/API Gateway/S3/EC2) for zero-downtime deployments, and implemented WebSocket real-time messaging plus production computer-vision object detection.

fastAPI React Vue.Js CI CD AWS Lambda AWS EC2 WebSockets Microservices

Full Stack Developer

BILT S.A.

Mar 2023 - Mar 2024 (1 year)

Cut API response times from 1,500 ms to 40–100 ms (-97%) through SQL query optimization, PostgreSQL indexing, and business logic refactoring. Refactored legacy frontend/backend, increased unit test coverage, stabilized recurring outages, and developed backend APIs with Node.js/Express and MongoDB for web and mobile applications.

SQL Query Optimization API Development MongoDB Unit Testing Refactoring Performance Optimization Production Uptime Stabilization

Backend Developer

Wahtari GmbH

Jan 2020 - Mar 2023 (3 years 2 months)

Built and maintained Python and Node.js RESTful APIs serving web and mobile applications in production across international distributed teams. Integrated backend systems with IoT devices via Bluetooth and WiFi, optimized database performance across relational and non-relational stores, and established unit testing and technical documentation standards to reduce production defects.

REST APIs Backend IoT Integration (Bluetooth WiFi)RESTful APIs Unit Testing Technical Documentation