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Full-stack developer and Computer Systems Engineering graduate. I build modern web apps with TypeScript end to end — React/Next.js front ends on Node.js/Express REST APIs and PostgreSQL (Supabase/Neon).
I care about software that stays maintainable, not just software that runs: strict typing across the stack, automated tests with Vitest and Playwright, and GitHub Actions CI/CD on every commit. I work in Agile/Scrum, design REST APIs, and document the reasoning behind my decisions with Architecture Decision Records. Ongoing Business Administration studies keep me focused on the process and goals behind the code.
I work comfortably in English (C1) and Spanish (native).
Also in the toolbox — Payload CMS · Prisma ORM · Zod · TanStack Query · React Hook Form · shadcn/ui · REST API design · SOLID · Architecture Decision Records (ADRs) · Conventional Commits · Claude Code · LLM integration (Vercel AI SDK) · RAG (pgvector, hybrid retrieval, eval harness)
RAG assistant that answers the tax and social-security questions of self-employed people in Costa Rica, in plain Spanish, with every material claim cited to the official Hacienda or CCSS document and article it came from. Hybrid retrieval (pgvector + lexical search fused by reciprocal rank, then reranked) over 23 official documents; each answer is checked against its sources before it streams, and the assistant abstains or routes to the right institution when the corpus can't back it. Next.js 16 + TypeScript (strict) on Supabase (PostgreSQL, pgvector, row-level security), Claude via the Vercel AI SDK, gated by a 73-case eval harness (retrieval hit-rate · groundedness · abstention) alongside Vitest, Playwright, and GitHub Actions CI. Solo build directing coding agents, with 21 Architecture Decision Records and a written account of how it was built. Apache-2.0.
Educational-management platform I built and delivered to a Costa Rican non-profit — students, courses, attendance, grading, and in-browser certificate PDFs across four roles (admin · teacher · student · community-service trainee). Originally shipped on Supabase (Auth, RLS, PostgreSQL), then rearchitected into a zero-backend, always-on demo so anyone can tour every role without a login. React 18 + TypeScript (strict), Vite, Tailwind, and shadcn/ui, gated by a 7-step GitHub Actions pipeline (type-check · lint · format · i18n · Vitest · build · Playwright) on every commit. Bilingual (EN/ES) with CI-enforced translations.
- LinkedIn — linkedin.com/in/rjwrld
- Email — rjcalderonb@outlook.com