Alex Castillo Gonzalez
@alexcastillogonzalez
Python/AI engineer: RAG and MCP agents with eval harnesses, deployed on AWS. 110 merged open-source PRs (LangChain.rb, Haystack).
Dominican RepublicWhat I'm looking for
Software / applied AI engineer in Python, TypeScript and Ruby, based in Santo Domingo (UTC-4), Spanish passport, Spanish native and professional English. Looking for junior or mid-level remote work: software engineering, QA, technical support or AI training.
Since July I’ve had 110 pull requests merged across 32 open-source projects, with a median of under a day to merge: 29 in LangChain.rb (LLM-provider and tool-calling layer), 12 in Haystack and its integrations (concurrency and async/sync-parity defects), 12 in the Rails app Sure, plus fixes in pydantic-ai, opik, phoenix, pipenv and pdm.
Projects: Business Ops Agent, an MCP server and LangGraph agent deployed on AWS (Lambda, DynamoDB, Terraform, GitHub Actions with OIDC) with a trajectory-evaluation harness; Ask the GDPR, a RAG system that cites the exact provision and declines when the source doesn’t cover the question; and ragcite, the evaluation library extracted from it.
Earlier: fullstack Rails developer at TECNOBIT (2022), Ruby/SQL teacher at Le Wagon, and I ran my own small business in Spain and Toronto.
Experience
Work history, roles, and key accomplishments
Founder & Developer
Churrería Calderón
Dec 2025 - Present (10 months)
Built and deployed the business website and designed an embeddable AI chat widget that answers customer questions grounded in the business's own data. Turned the widget into a reusable, productized pattern now offered to other small businesses.
Ruby on Rails Instructor
Le Wagon
Sep 2022 - Oct 2022 (1 month)
Taught Ruby on Rails fundamentals, guiding learners through building and reasoning about web applications.
Fullstack Developer Intern
Tecnobit (Grupo Oesía)
Jun 2022 - Sep 2022 (3 months)
Built front- and back-end features for a long-running production app within an established engineering team.
Education
Degrees, certifications, and relevant coursework
Le Wagon
Fullstack Web Development Bootcamp, Web Development
Completed a fullstack web development bootcamp, focusing on Ruby on Rails and modern web development practices.
Tech stack
Software and tools used professionally
Availability
Location
Dominican Republic
Canada
SpainPortfolio
portfolio-alexgonzalez33.vercel.appSalary expectations
Job categories
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