Career history, current role at Monest, and areas of expertise.
Ruan Gustavo is a software engineer based in Brazil who builds AI products with TypeScript and React. He started programming out of curiosity and still does it outside work. That curiosity pulls him toward AI, systems, and products where complexity has to become clear to the person using them.
At Monest, a Brazilian fintech for debt collection and negotiation, Ruan works on MIA, an AI agent that negotiates with debtors over WhatsApp and voice calls. MIA handles more than 2 million messages a day and has recovered over $150 million in debt.
He owns agent architecture, evaluation, and observability for MIA. That includes an evaluation pipeline that cut false positives by 5.5 times, the tooling the agent uses to calculate and present deals, and the tracing that lets the team see why the agent said what it said.
Ruan helped build Pethis, a management platform for veterinary clinics and pet shops, from the start: scheduling, clinical records, sales, and invoicing.
At Loomi, a Brazilian software studio, he designed AI agents for Brazil's National Council of Justice (CNJ).
He also built backend-for-frontend layers for Vivo's CRM, in an operation with more than 15,000 call-center operators.
LLM agent architecture and tool design, evaluation pipelines for conversational AI, observability and tracing for LLM systems, TypeScript and Node.js backends, React and Next.js frontends, and WhatsApp and voice conversational products at scale.
Outside work Ruan contributes to open source, mostly pull requests and issues on tools he uses every day.