David Refugio Alejos

About

High-impact Senior AI Full Stack Engineer with 8+ years of experience architecting production-grade AI systems and scalable web applications. Expert in the latest Generative AI stacks (Azure AI Foundry, AWS Bedrock, OpenAI), Multi-Agent orchestration, and RAG pipelines. Proven track record of migrating legacy workflows to autonomous agents using GPT-4o and Claude 3.5 Sonnet, resulting in 70%+ operational cost reductions. Deep expertise in React, Python, and Cloud Infrastructure (AWS/Azure), delivering enterprise solutions that bridge complex backend logic with intuitive frontend experiences.

Experience

• AI Full-Stack Engineer · Beejern06-01-2023 –

  - Orchestrated an enterprise-grade AI agent platform & small content agents using Azure AI Foundry and Microsoft Copilot Studio, integrating deeply with M365 graph data to automate complex internal compliance workflows, reducing manual labor by 72%.\n- Led the migration from legacy models to state-of-the-art GPT-4o and Claude 3.5 & 3.7 Sonnet, utilizing advanced Prompt Engineering techniques to improve reasoning capabilities and reduce token usage costs by 40%.\n- Deployed autonomous customer service agents using AWS Agent Core (Bedrock), enabling self-service resolution for lots of users and cutting support ticket volume by 65%.\n- Constructed a high-performance Retrieval-Augmented Generation system with hybrid retrieval (Pinecone + Weaviate) and recursive indexing, achieving over 92% answer accuracy on a 20 million+ document corpus by implementing re-ranking strategies.\n- Integrated AWS QuickSight embedded dashboards into a React frontend, providing real-time analytics on agent performance and token consumption for executive stakeholders.\n- Migrated inference workloads to self-hosted fine-tuned Llama 3.1 using vLLM, cutting annual inference costs by over $800,000 while maintaining sub-500ms latency.\n- Engineered a streaming UI with React Server Components and Server-Sent Events (SSE) to display token-by-token generation, achieving a sub-200ms Time-to-First-Token (TTFT) experience.

• AI Full-Stack Developer · Paralect04-01-2021 – 03-01-2023

  - Designed and deployed a company-wide AI assistant using LangChain and OpenAI function calling, adopted by over 5,000 employees, and consistently ranked as the top internal productivity tool.\n- Implemented a document processing pipeline with Unstructured.io and LayoutLM, converting more than 300,000 PDFs monthly into a structured Qdrant-backed RAG system for instant information retrieval.\n- Reduced model hallucinations by 95% by establishing a 'LLM-as-a-Judge' evaluation framework using Giskard, ensuring strict adherence to corporate guardrails.\n- Developed a React-based chat interface supporting markdown rendering, code highlighting, and session history management, providing a seamless UX similar to consumer-grade AI tools.

• Full Stack Engineer · Airdev08-01-2017 – 02-01-2021

  - Directed the development of a Next.js analytics dashboard serving 50K daily active users (DAU); integrated an early NLP query layer allowing non-technical users to query data using natural language.\n- Spearheaded the end-to-end full-stack development of a resource management system on AWS (Python/Flask + React), improving the assignment speed of 200+ global engineers by 40%.\n- Devised a real-time SLA compliance system with GraphQL APIs and AWS Lambda alerting, contributing to a 25% reduction in SLA breaches within three months.\n- Launched a mobile-first React application for field technicians to log network hardware data, reducing manual entry errors by 60% through automated validation and offline-first capabilities.\n- Re-architected SQL schemas in PostgreSQL and implemented Redis caching layers, achieving sub-50ms API response times under high-concurrency loads.

• Frontend Developer · Vinova11-01-2015 – 04-01-2017

  - Delivered production-grade frontends using React, TypeScript, and Tailwind. Reduced application load times by 40% through code splitting, lazy loading, and aggressive bundle optimization.\n- Visualized real-time financial data using React, Chart.js, and WebSockets, providing instant operational insights for enterprise clients.\n- Established a shared reusable component library, reducing UI development time by 35% and ensuring brand consistency across web and mobile platforms.

Education

• Baker UniversityBachelor of Science, Computer Science

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