I bring production rigor to AI systems.
Full-stack Senior Software Engineer with 6+ years building high-volume products with React, Next.js and Java/Spring — now applying that same rigor to AI. I design LLM-powered systems with explicit guardrails against hallucination, not just prompts wired to an API. Today I lead frontend for Red Ventures’ solar energy vertical (~30% conversion uplift in Q1) while building production AI systems on the side.
I’m José Vinícius — a full-stack Senior Software Engineer from Pernambuco, with 6+ years spanning the frontend of products that convert and the backend of systems that scale. Right now, I’m channeling that foundation into AI engineering.
I’ve led frontend for Red Ventures’ solar energy vertical and built, at Livelo, a points → PIX platform that became one of the company’s largest products. That product sense rests on years of backend work in high-throughput fintech (Java/Spring, Kafka, Kubernetes), giving me a genuine full-stack view on architectural decisions.
That move into AI isn’t theoretical. In Personal CFO, a full-stack app I designed and built end to end, I use Spring AI and the OpenAI API to generate financial insights — but the model never computes a number: a deterministic backend calculates every KPI, and a guardrail layer validates the AI’s narration against that data before it ships, flagging anything that drifts instead of publishing it. Same instinct that drove my fintech work: the model doesn’t get to be a black box near real numbers.
Reliability isn’t a detail. It’s the feature.
Senior Software Engineer
Leading frontend engineering for the solar energy vertical — React/Next.js + TypeScript conversion experiences, in partnership with Vistra, driving ~30% conversion uplift in Q1 and ~60% cumulative growth. Built a Storybook + Tailwind design system consumed by multiple teams and a GraphQL layer that cut API latency by ~90%.
Senior Software Engineer
Built the points-to-PIX conversion platform — within months, one of Livelo’s largest products, redeeming millions of points monthly: bank integrations, a complex settlement workflow, balance management and payment batches. I also developed the PIX module in Livelo’s React Native app.
Senior Software Engineer
Designed the interchange fee estimation and billing system, processing ~3–4 million records daily, with event-driven pipelines (Kafka, RabbitMQ, Spring Cloud) on Kubernetes. Also delivered internal Angular and Next.js modules for offer configuration and fee management.
Technical Writer
Authored Spring Boot articles for a global developer audience, translating complex backend engineering concepts into actionable technical guidance.
Senior Mobile Developer
Delivered React Native features inside Banco do Brasil’s Social Security app — serving ~2.5M users — working across mobile UI, API integration and release constraints in a high-visibility banking environment.
Software Developer → Senior Software Engineer
Built a payment checkout platform deployed across major Brazilian utilities (Celpe, Compesa, Cosern, Enel), enabling continuous billing during COVID-19. Promoted from Junior to Senior in under 2 years. Engineered a metrics platform that evolved from weekly manual reports to daily — and later real-time — reporting.
B.Sc. in Economics
A quantitative grounding in economics, statistics and modeling — a different lens on financial-systems problems.
Featured projects
Real-time Interchange+ Calculator
Real-time calculation of card-brand interchange fees (Mastercard, Visa, Elo), built on event pipelines processing ~3–4 million records daily.
Open Finance Accounting Platform
An Open Finance platform for Dcifre (accounting), centralizing and controlling its clients’ many bank accounts.
Bacen Resolution 4.966 compliance
Adapting accounting criteria to the new rules of Bacen Resolution 4.966/2021, adjusting the treatment and classification of financial instruments in the platform.
Payment Totems & Online Checkout
Co-led Celpe’s payment totems and Flexpag’s online payment rollout during the pandemic, keeping billing alive for utility companies.
Receivables · Resolution 264 (CERC)
Architecture of a system that calculated the receivables of the companies served (Flexpag was a sub-acquirer for Celpe, Cosern, Elektro and others), plus generating and sending the batches to CERC (the receivables registry), following financial-market infrastructure standards.
Skills
From the frontend that converts to the backend that scales — and now, the AI layer built with the same rigor.
- Spring AI
- OpenAI API
- Prompt Engineering
- Hallucination Guardrails
- Structured Output Parsing
- React · Next.js
- React Native
- TypeScript
- Storybook
- Tailwind CSS
- Angular
- Spring Boot
- Spring Cloud
- NestJS
- GraphQL
- REST · Express
- TypeScript
- JavaScript
- Java
- Python
- Go
- Apache Kafka
- RabbitMQ
- PostgreSQL
- Oracle DB
- Cassandra
- Docker
- Kubernetes
- GitHub Actions
- Jenkins
Writing
Technical notes and essays, published on Medium.
Building a PIX Settlement Simulator with Java Virtual Threads
Modeling concurrency and payment settlement at scale on the JVM.
Por que pássaros conseguem voar e humanos não?
An essay on freedom, limits and Brazilian neoliberalism.
Let’s build something.
Open to freelance, projects and new opportunities. Drop me a line — I reply fast.
[email protected] →