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Facet · Apps

App Development

From data model to app store — the whole product, one person.

Full-stack, to me, isn't 'I know some front-end and some back-end'. It's carrying the whole product in your head: the data model, the backend, the UI, the mobile app, the deploy — and the scope cuts that make it fit the deadline. My argument isn't seniority on a slide: it's apps live, with real users, real payments, and real operations. Built from zero, solo, and kept alive.

Ruby on Rails 8 Hotwire / Turbo React Native / Expo Solid Queue PostgreSQL PIX & Payments Realtime (Streams · Cable) PWA & Web Push DigitalOcean (auto-deploy) Data Modeling Ruby on Rails 8 Hotwire / Turbo React Native / Expo Solid Queue PostgreSQL PIX & Payments Realtime (Streams · Cable) PWA & Web Push DigitalOcean (auto-deploy) Data Modeling
Talk to me 📄 CV — Senior Full-Stack (PDF)
0 Years shipping product end to end
0 Personal apps built from zero, solo
0 Platforms: web, iOS, and Android
0 Green tests in the Salgadelli app

My stack is opinionated because speed comes from decisions already made: Rails 8 with Hotwire for web that feels like a SPA without paying the SPA tax, Solid Queue for jobs, PostgreSQL for everything, DigitalOcean with auto-deploy from git. When the product calls for a real app, React Native with Expo joins the monorepo. A new project starts with that foundation ready — the time goes into what's unique to the product, not into rewiring infra.

Range matters more than the count: a gig-work marketplace with a PIX wallet, bidirectional reviews, and real-time chat (Free Diária); the complete operation of a brick-and-mortar shop — orders, menu, a kitchen on a TV, a counter kiosk (Salgadelli); an MMO football manager with a single shared world, live matches, and a closed economy (Boleiragem). Three completely different product problems, solved with the same fundamentals: honest modeling, UI that responds instantly, and deploys without ceremony.

Behind the personal apps sits a decade of large systems: an enterprise migration reconciled to the cent in the US (Monument), a re-architecture with 99%+ gains and an AI platform at VIK, a mesh of 50+ microservices at Brazil's largest digital insurer (YOUSE), 1M-records/day batches in banking, and a traffic system with 99.9% uptime. That ballast is what makes a solo-built app hold up in production.

Architecture

The foundation of every app: Hotwire and React Native clients over a tidy Rails 8 monolith — jobs in Solid Queue, PostgreSQL as the source of truth, and automatic deploys from git to live.

Projects

Through this lens

Multimodal · Sports Live

SelfScore

Amateur football analytics. Multi-camera video pipeline + GPT Vision + real-time WebSocket coaching.

As a product, SelfScore is a React Native/Expo app with a Rails backend doing genuinely heavy lifting: multi-camera footage upload, a 5-phase video pipeline running in background jobs, and analysis arriving over WebSocket while it processes. Gamification with XP, levels, and trophies, real-time chat, per-player profiles — amateur football with big-product treatment.

Impact
  • RN/Expo app + Rails 8 in the same monorepo, with a store pipeline
  • Heavy video hidden behind simple UX: upload the footage, get the analysis
  • Full gamification: XP, levels, trophies, rankings, and real-time chat
Stack
Rails 8 + React Native (Expo) Gemini Vision FFmpeg Whisper WebSocket (8 tools in-flight) Sidekiq
Live →
Marketplace · Mobile Live

Free Diária

Gig-work marketplace. Intelligent matching, swipe discovery, PIX wallet.

A two-sided marketplace built solo: professionals and employers with intelligent matching, swipe discovery, a digital wallet with PIX, bidirectional reviews, and real-time chat. And the product includes what nobody sees: an internal showroom with 208 documented screens, 146 UI evals, and the store publishing pipeline — EAS, Play Console, App Store — run single-handedly.

Impact
  • Two sides + real money: PIX wallet, matching, and bidirectional reviews
  • A 208-screen showroom + 146 UI evals as a quality discipline
  • Full store pipeline: EAS Submit, Play Console, and App Store
Stack
Rails React Native Stripe + PIX Google Maps PostgreSQL
Sales & Operations Live

Salgadelli App

Full sales and operations app for a real business: orders, menu, kitchen, kiosk.

Operations software for the family's brick-and-mortar shop: customers order, the counter sells in kiosk mode, the kitchen sees everything on a Kanban on the TV, the admin closes out the operation. Built end to end (S0–S8) with 291 tests and 13 evals green. And the detail that teaches the most: the users aren't early adopters — they're cooks with their hands in the dough. The UI has to be obvious or it dies.

Impact
  • Order → kitchen (KDS on a TV) → counter, in a single flow
  • Kiosk mode + web push + shop operations admin
  • 291 tests + 13 evals in a snack-shop app — rigor isn't optional
Stack
Ruby on Rails 8 Hotwire Solid Queue Web Push (VAPID) PostgreSQL
Live →
Game · Living World Live

Boleiragem

MMO football manager with a single living world, live matches, and a closed economy.

As app engineering, Boleiragem is proof of what Hotwire can take: an MMO game as a single living screen — zero reloads, everything through Turbo Streams and Stimulus — on top of a live match engine with a hybrid-elastic clock, a single shared world, and a closed economy with a ledger. The heavy work runs in jobs and arrives by broadcast; it feels like a game, not a dashboard.

Impact
  • A real Hotwire SPA: zero reloads, job + broadcast for everything heavy
  • Live match engine with a hybrid-elastic clock and an immutable past
  • Closed economy with a ledger — every coin traceable end to end
Stack
Ruby on Rails 8 Hotwire (SPA · zero reload) Solid Queue Claude (AI manager via tool calls) PostgreSQL
Also in: Agents
Live →
Game · Betting Pool Beta

Chá de Palpitê

Gamified baby-shower betting pool with rankings, guesses, and PIX.

The smallest app in the portfolio and the argument for finish: a baby-shower betting pool with guesses, a live leaderboard, and PIX entry. Small scope treated with the same rigor — clean modeling, Hotwire so the leaderboard updates instantly, tested scoring rules. Small software done well is portfolio too: craft doesn't depend on size.

Impact
  • Guesses, scoring, and a live leaderboard with Hotwire
  • PIX entry with manual verification — pragmatism sized right
Stack
Ruby on Rails 8 Hotwire PIX
Experience

The track record, re-read

Aug 2025 – May 2026

Senior Data Migration Engineer · AI-Augmented

Monument (Remote, US)

  • Financial data from dozens of enterprise clients unified into a single schema — interest, fees, and amortizations reconciled to the cent
  • Internal tooling treated as product: every new migration client onboarded faster
Claude Code TypeScript Node.js MySQL AWS
May 2023 – Jul 2025

Principal Software Engineer · AI Platform Lead

VIK (Remote)

  • Re-architecture with 99%+ gains: dashboards that took hours started answering instantly
  • Vik Nutri from agent design to mobile UX — a complete AI product for 1,000+ users
  • Monolith → distributed: bounded contexts and messaging (Kafka, RabbitMQ) without stopping the operation
Ruby on Rails React OpenAI · Claude · Gemini OpenRouter · LiteLLM Kafka · RabbitMQ BigQuery · Looker
Nov 2022 – May 2023

Senior Software Engineer (Consultant)

META | YOUSE — Caixa Digital Insurance (Remote)

  • Node/Ruby microservices inside an event-driven mesh of 50+ services
  • React dashboards for claims analytics + AWS deploys with CI/CD
Node.js Ruby React AWS (S3, RDS, ECS) Kafka
Sep 2021 – Nov 2022

Software Engineer

Adminer (Remote, B2C)

  • B2C analytics platform handling millions of requests/day
  • Chrome extension with 50,000+ downloads — a complete product inside the product
Node.js Ruby Angular PostgreSQL MongoDB Elasticsearch
Nov 2020 – Nov 2021

Java Software Developer

MJV Technology & Innovation | Bradesco Insurance (Remote)

  • Async batches of up to 1M records/day for the insurance operation of one of the country's largest banks
  • PostgreSQL tuning that cut average query time by 60%
Java Spring Boot PostgreSQL Apache Airflow
Jan 2017 – Nov 2020

Java Developer

PSG | DETRAN — Government Traffic Dept. (Remote)

  • Full lifecycle of a government traffic-violation system — millions of vehicles, 99.9% uptime
  • Relational modeling, internal tooling, and DevOps end to end
Java Spring Boot PostgreSQL Heroku
Skills

The toolkit for this lens

⚙

Backend & APIs

Robust APIs and scalable systems with a focus on correctness, performance, and operational sanity.

Ruby on Rails 8 Python (FastAPI) Node.js / TypeScript REST · GraphQL · SSE Sidekiq · Solid Queue Background Jobs
📱

Frontend & Mobile

Hotwire-first for AI-native dashboards, React Native for mobile. Real-time UIs that don't fight you.

Hotwire / Stimulus / Turbo React / TypeScript React Native / Expo Tailwind CSS WebSocket UIs
📊

Data & Vector Stores

Schema design, query tuning, RAG over proprietary data. pgvector-first, lifted from production scars.

PostgreSQL (tuning · partitioning) pgvector / RAG BigQuery · Looker Elasticsearch MongoDB · MySQL ETL & Data Migration
🧭

Engineering Craft

Patterns, models, and clean architecture — the stuff that makes the codebase outlive the deadline.

Design Patterns · SOLID Clean Architecture Data Modeling TDD · BDD (RSpec · Jest) Refactoring at Scale

Need someone who ships the whole product?

From data model to app store — senior/staff full-stack to build, unblock, or scale a product. Rails, React Native, and the messy middle between the two.

Talk to me 📄 CV — Senior Full-Stack (PDF)
SB
Sérgio Brito
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