Jasmin Castillo

Staff/Principal-level Software and AI Engineer with 8+ years of experience designing, building, and evaluating production-grade systems across AI, machine learning, web, cloud, and data-intensive applications. Specializes in the intersection of software engineering and AI model development, with deep expertise in LLM evaluation, post-training data, coding-model evaluation, AI agents, and expert-in-the-loop workflows. Recognized for reading generated code with a critical eye — reproducing failures, tracing complex execution paths, weighing architectural trade-offs, and judging whether AI-generated solutions are genuinely production-ready.

Guided by a commitment to correctness over surface-level output, reproducibility over guesswork, and clear technical reasoning over quick answers.

Staff / Principal Software & AI Engineer - Tek4Real

(2026-02)

• Design and deliver production-grade web, backend, cloud, and AI-powered systems across complex business domains.
• Architect scalable full-stack applications using React, Next.js, Node.js, Django, PostgreSQL, MongoDB, Docker, and AWS, backed by modern CI/CD practices.
• Build LLM-powered workflows spanning retrieval, structured generation, evaluation, prompt orchestration, and automated quality checks.
• Evaluate AI-generated code and technical solutions for correctness, maintainability, security, performance, architecture, and production readiness.
• Design evaluation criteria and structured test cases to assess model behavior across ambiguous, multi-step engineering scenarios.
• Investigate model and application failures through reproducible test cases, error analysis, and root-cause debugging.
• Work across frontend, backend, APIs, databases, and cloud infrastructure to evaluate complete systems rather than isolated model outputs.
• Develop reusable engineering patterns, automated testing, and CI/CD pipelines to improve reliability and maintainability.

AI/ML Engineer - Google Gemini Omni

(2023-08 - 2025-12)

• Designed and developed production-grade AI/ML solutions focused on large language models, generative AI, NLP, and intelligent automation.
• Built and optimized ML pipelines for training, evaluation, inference, and deployment, with an emphasis on scalability and reliability.
• Worked with transformer-based architectures, LLM prompting, fine-tuning, RAG, embeddings, and vector search.
• Developed Python-based ML services and APIs to integrate AI models into scalable production applications and data pipelines.
• Implemented automated evaluation and benchmarking workflows to assess model quality, accuracy, robustness, latency, and failure modes.
• Collaborated across engineering and research teams to translate ML research concepts into reliable production systems.
• Improved model-serving and inference performance through distributed processing, caching, and efficient data pipelines.
• Applied software engineering best practices, including testing, CI/CD, containerization, monitoring, and cloud-based deployment.

Senior Full-Stack Engineer - American Express

(2019-04 - 2023-05)

• Designed and developed scalable full-stack web applications using React, Next.js, TypeScript, Node.js, NestJS, Django, and PostgreSQL.
• Built modern, responsive frontends with reusable component architectures, state management, and optimized REST/GraphQL APIs.
• Developed secure backend services, authentication systems, payment integrations, and third-party API integrations.
• Designed relational and NoSQL database architectures using PostgreSQL, MySQL, MongoDB, and Redis.
• Built and deployed cloud-native applications using Docker, AWS, GCP, Kubernetes, and CI/CD pipelines.
• Developed multi-tenant SaaS platforms with role-based access control, subscription management, analytics, and admin dashboards.
• Integrated AI/ML capabilities, LLM APIs, RAG pipelines, and embeddings into production web applications.
• Improved application performance, reliability, and security through architectural optimization, caching, and automated testing.
• Collaborated with product managers, designers, and engineers to deliver products from requirements through production.

Freelance Software & AI Developer - Self-Employed

(2016-02 - 2019-03)

• Designed and built custom web applications and data-driven solutions for small-to-medium businesses using modern tech stacks including React, Next.js, Django, and PostgreSQL.
• Developed and deployed Python-based automation scripts and data processing pipelines to help clients analyze large datasets and improve business operations.
• Drove continuous professional development by mastering new technologies, including TypeScript, cloud infrastructure (AWS/GCP), and early-stage AI/ML frameworks and libraries.
• Managed all aspects of the project lifecycle — requirements gathering, architecture, development, testing, and deployment — ensuring timely delivery and client satisfaction.
• Transitioned from academic computer science into full-stack and AI engineering, building a robust portfolio of production-grade applications.

Bachelor of Science - Computer Science - University of Colorado Boulder (2011 - 2016)