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// fullstack developer · web & mobile

Rômulo Valentim

Rômulo Valentim

I build across the full stack — from the pixel to the database.

Full-stack developer with 4+ years building production web and mobile apps in health tech, based in Natal, Brazil, open to remote. End-to-end with React, Next.js, React Native, Node.js, and Firebase — most recently on Fully, a wellness and rewards app affiliated with Prudential, with 122K+ active users — day-to-day work with the local, Portuguese-speaking team, plus occasional English-language meetings with international teams.

Before that, I spent three years at DNA Center — growing from intern to acting Tech Lead of an 8-developer team — on mission-critical systems — lab queuing, medical document storage, microbiological tracking — used daily by 300+ employees across 40 units.

I also build my own products, like Lumen — a multilingual microlearning app where I handled idea, design, development, and marketing myself.

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Front-end

Design systems, micro-frontends, accessibility, native Kotlin/Swift modules

Back-end

APIs, authentication, microservices, real-time systems

Data

SQL, NoSQL, cloud storage, ORMs (Prisma/Sequelize)

Infra

CI/CD, automated testing, Vercel deploys, Git, agile process, desktop packaging

the stack, exploded — Click a layer to jump to the tech behind it.

// experience

Timeline

Roles and the work behind them.

  1. Jun 2025 – Jul 2026

    Fully Ecosystem

    Full Stack Engineer

    Built the Fully app — a wellness and rewards platform affiliated with Prudential Financial, with 122K+ active users — with React Native, native Kotlin/Swift modules, and a NestJS + PostgreSQL/MongoDB back end. Redesigned authentication with ForgeRock (40% faster), integrated Samsung Health, Apple Health, and Health Connect, and built the Next.js admin tooling.

    Read more
    • Personalized weekly goals system for each user, covering physical activity, nutrition, and mental health, with coin rewards.
    • Native Kotlin (Android) and Swift (iOS) modules syncing user health data from Samsung Health, Apple Health, and Health Connect into the React Native app.
    • Migrated the weekly goals and coin rewards features to new APIs after a partner discontinued its platform — mapped every front-end and SDK call to the old system, switched them over, and tested each flow to catch breakages.
    • Next.js/TypeScript admin dashboards for the operations team (user data, goal progress, coin balances, health integrations), plus NestJS back-end features covered by end-to-end tests.
    • A handful of English-language meetings with Prudential teams to align on product priorities, architecture, and bug fixes — day-to-day work was with the local, Portuguese-speaking team.

  2. Apr 2022 – Jun 2025

    DNA Center

    Full Stack Engineer

    Grew from intern (Apr 2022) to Full Stack Engineer (Jan 2023) to acting Tech Lead of an 8-developer team (Dec 2024) — architecture, code reviews, coding standards, and mentoring — on systems used daily by 300+ employees across 40 laboratory units. Built the company's design system from scratch, a real-time lab queuing system (50% shorter patient wait times), the platform storing millions of medical documents, and CI/CD with Jest, Cypress, and GitHub Actions.

    Read more
    • Real-time queuing system: a Next.js web app plus a React Native Android TV app on Firebase Firestore, using transactions so the same patient is never called twice.
    • Puppeteer/Selenium bots automating exam authorization across insurance providers — one bot per provider, retrying and skipping failures without blocking the cycle — cutting manual authorization time by over 80%.
    • Clean Architecture on new projects, with a Jest unit test per use case in the TypeScript/NestJS back end, plus Cypress integration and e2e tests.
    • Blood sample microbiological tracking system, focused on traceability and quality control.
    • Internal task-management tool (Scrum/Kanban), inspired by Jira/Trello, built from scratch to streamline the teams' workflow.
    • Employee productivity dashboard with automated calculations and dynamic visualizations tied to operational data.
    • Billing reconciliation platform for insurance partners, centralizing data and automating previously manual processes.

  3. Feb 2023 – Jun 2025 · alongside DNA Center

    AvaliarMe

    Full Stack Engineer (Freelance)

    Freelance work done in parallel with my full-time role at DNA Center. Built a QR-code customer feedback platform with Next.js, Tailwind CSS, and Firebase, where customers rate the establishment and the staff member who served them — hundreds of ratings a day across 50+ establishments, with automated deploys on Vercel.

    Read more
    • AI chat assistant (OpenAI API) in the establishment dashboard that analyzes ratings and comments for a selected period and suggests improvements to owners.
    • ~200 monthly WhatsApp Business API (Meta) notifications sending feedback summaries to owners, through Google Cloud Scheduler jobs with retries, error logging, and duplicate-send checks.
    • Interactive clinical dashboards with automatic report generation and personalized PDFs per profile — monthly reports went from ~2 hours of manual counting to a one-click download.

Education

  • 2017 – 2023

    IFRN — Federal Institute of Rio Grande do Norte (Natal Central)

    Undergraduate Technologist Degree in Systems Analysis and Development

    A federal, publicly funded institution. Capstone thesis: a scientific paper on the medical-document digitization system I built professionally at DNA Center — turning real production work into an academic case study.

// skills

Toolbox

Languages first, then organized by the layer of the stack each tool lives in.

Languages

HTMLCSSJavaScriptTypeScriptSQLKotlinSwiftPython

Front-end

ReactNext.jsReact NativeExpoNativeBase / gluestackMaterial UITailwind CSSReact QueryZustandReact Hook Form

Back-end

Node.jsNestJSExpressOpenAI API

Data

PostgreSQLMongoDBSQL ServerFirebaseSupabasePrismaSequelize

Infra

GitGitHub ActionsVercelDockerGCPAWSJira / AtlassianJestSeleniumPuppeteerCypressStorybookFigmaTauriElectron

// personal projects

Personal projects

Work built on my own time — real products, client work, and technical challenges. What I did at each company is detailed in the experience section above.

Lumen

2026

React Native (Expo)

A multilingual (PT/EN/ES) mobile microlearning app: 10–15 minute sessions across 12 knowledge tracks (philosophy, history, psychology, science, and more), designed and built end to end — product, UI design, development, and marketing.

Front-endBack-endData
Read case Live demo

Forge

2026

React Native (Expo) · Next.js

A diet- and workout-tracking app, available on both web and mobile, letting people log meals and training sessions in one shared product.

Front-endBack-end
Read case Repository

Uber App

2024

React Native (Expo) · Kotlin · Firebase

A ride-hailing style app with real Google location integration — live geolocation, interactive maps, and address autocomplete.

Front-endBack-end
Read case Repository

Price Tracker

2026

Next.js · TypeScript · Firebase

A price-monitoring tool that tracks products across Amazon, Mercado Livre, Magazine Luiza, and KaBuM!, scraping prices daily and sending a Telegram alert whenever one drops below a target.

Front-endBack-endDataInfra
Read case Repository

Info Shield

2025

React Native (Expo) · Kotlin · Swift

A take-home technical challenge built to join Fully Ecosystem: an Expo/React Native app with authentication and form validation, a native module written in Kotlin and Swift, and in-app theme switching.

Front-endBack-end
Read case Repository

CodePix

2024

Go · Domain-Driven Design

A Full Cycle course project: a Pix-style payment system built in Go with a layered, domain-driven design architecture — an architecture study, not an original product design.

Back-endData
Read case Repository

// contact

Let's build something

Open to fullstack roles, remote-first. The fastest way to reach me is email.

Email me Resume (EN) Currículo (PT)

Elsewhere