I'm a software engineer from Brazil with a postgraduate degree in Data Science (PUC-Rio). I've spent 14 years on backend and full-stack systems for fintech, logistics and education, and these days I bring AI into real products. Almost everything below has a demo you can open right now.
jeffersonvalandro.com.br · LinkedIn · Kaggle · 🇧🇷 em português
| Project | What it does | Stack | |
|---|---|---|---|
| Lastro | CRM for real estate agencies. An AI assistant proposes actions and the agent confirms them. | FastAPI · PostgreSQL (RLS) · React PWA · Claude | demo |
| InvestLink | Stock and REIT screener for the Brazilian market with an explainable score, built on audited CVM filings. | Flask · React · PostgreSQL · pandas | demo |
| InvestLink MCP | MCP server with RAG (pgvector + EmbeddingGemma on CPU) and read-only SQL. The demo shows every tool call live. | Python · MCP · pgvector · Gemini | demo |
| Vizion | BI without SQL: ask in plain language, get charts and dashboards grounded in real queries. | Next.js · FastAPI · DuckDB · Claude | demo |
| ARIA | Personal assistant that turns text or voice into events, tasks and notes through function calling. | Next.js · Prisma · Gemini · PWA | demo |
| Tradelink | Trade journal and multi-indicator backtesting engine with an async job queue. | React · NestJS · FastAPI · BullMQ | demo |
- hollowtest: finds tests that pass even when the code is broken (no assertions,
toBeNullwithout(), asserts that only run incatch, unawaited.resolves). JS, TS and Python, on npm, with an ESLint plugin and a Claude Code plugin. Try it in the browser → - swing-quant: quantitative swing-trading system validated with walk-forward and Monte Carlo, plus a 16-year study on whether it beat simply investing.
- archlens-ai: points at a codebase and generates an interactive architecture report with health scores and dependency cycles.
- ai-dev-kit: spec-driven workflow, quality auditor and hooks to set up AI coding agents in any project.
- kairo-blocks-lite: 10 free landing-page blocks for Next.js 16, Tailwind CSS 4 and shadcn/ui. Demo
- Artificial Intelligence from the Inside: from predictive systems to LLMs and Transformers. Paperback on Amazon, also in Portuguese on Kindle.
- How to Pass Developer Interviews: from the résumé to the offer. Paperback on Amazon.
- Free PDFs, including Your First MCP Server and a children's book on how AI works: jeffersonvalandro.com.br/en/books
Production-ready Next.js 16 + Tailwind CSS 4 + shadcn/ui templates under the ValandroUI name: an admin dashboard, an AI SaaS starter, invoicing, booking, directory, real estate and more, each with a live demo. See them all →
Java · Spring Boot · Python · FastAPI · TypeScript · React · Next.js · PostgreSQL · Docker · LLMs (Claude, Gemini) · RAG · MCP