Artur Guerra

I build real products end to end.

Full stack developer and AI engineer. Multi-tenant SaaS, healthtech and LLM systems, from the first architecture sketch to the deploy, with AI wired into every layer. Not demos. Production.

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Available for new projectsNova Friburgo, Brazil · remote

Shipped and running

Seven systems designed, built and shipped, most of them solo, from the first migration to the last deploy. Each window runs a simulation of what its product does.

Vivi AI

AI assistant · Solar-energy SaaS

Running in production

Visol's production conversational assistant. A Python/FastAPI microservice that orchestrates OpenAI, Claude and Gemini with automatic fallback, runs an intent-handling agent with tool use and guides onboarding through a state machine, serving the company's Angular web app and Ionic mobile app.

automated tests
1,900+
pass rate
99.9%
LLM providers
3
Full manifest
  • Multi-provider LLM orchestration with automatic fallback
  • Intent-handling agent with tool use and multi-turn memory
  • State-machine guided onboarding
  • Retry and backoff with Tenacity, plus a permission layer over Visol's licensing model
  • CI/CD on GitHub Actions
  • Python
  • FastAPI
  • OpenAI
  • Claude
  • Gemini
  • Tenacity
  • GitHub Actions
Role: Designed and built it at VisolOpen the live product

EvoSolar Franquias

Solar energy · SaaS

Multi-tenant franchise management platform for solar energy companies. Handles onboarding, KPI tracking, royalty calculations, ad campaigns and internal communication across franchise units.

backend modules
34
lines of code
83k+
ad platforms
2
Full manifest
  • 34 backend modules with 83k+ lines of code
  • Google Ads and Meta API integration over OAuth
  • Google Gemini agents for conversational intelligence
  • WebSocket real-time chat with SLA tracking
  • Automated royalty calculations and financial sync
  • FastAPI
  • React
  • React Native
  • PostgreSQL
  • Redis
  • Celery
  • Docker
Role: Solo creator and developerPrivate codebase

Zelo App

Healthtech · SaaS

Medication management for families caring for elderly and chronic patients. Centralises drug schedules, caregiver coordination, dose tracking, stock and adherence analytics.

API endpoints
38
service domains
15
LLM providers
3
Full manifest
  • Multi-provider AI chain (OpenAI, Claude, Gemini) with automatic fallback
  • OCR medication extraction enriched with the ANVISA drug catalogue
  • Timezone-aware scheduling for multi-caregiver coordination
  • 38 specialised API endpoints across 15 service domains
  • LGPD compliance architecture with encryption and audit trails
  • FastAPI
  • React Native
  • Expo
  • PostgreSQL
  • Redis
  • Celery
Role: Solo creator and developerRead the public docs

Fantasy Picks

Sports & gaming · SaaS

Fantasy sports with survivor-style pick mechanics. Players buy picks to enter real football championships, choose teams each round and compete for prizes on real match results.

leagues covered
12+
wallet balances
2
async I/O
100%
Full manifest
  • Async-first architecture with asyncpg for high concurrency
  • Pick lineage tracking with complex business-rule validation
  • football-data.org integration across 12+ leagues
  • Dual-balance wallet (picks and prize money in BRL)
  • Clean Architecture with repositories and service layers
  • FastAPI
  • Next.js
  • TypeScript
  • Tailwind
  • PostgreSQL
  • Redis
Role: Solo creator and developerPrivate codebase

Also shipped

Three more systems, from a sports academy to a clinic running in production.

  • BR1 Sports Academy

    Sports management

    Academy management for young athletes, covering the whole lifecycle from first interest to advanced training, with coaches, doctors and psychologists working in one system.

    role levels
    6
    lines of Python
    17k+

    Flask · PostgreSQL · Bootstrap · Chart.js · ReportLab

  • Cesh

    Education · Social platform

    Academic social network for CEFET students. Pulls institutional data (schedules, grades, directory) into a modern platform with social features and automatic portal sync.

    PHP files
    190+
    credentials stored
    0

    PHP 8.3 · Slim 4 · MySQL · Docker · AWS S3

  • Pecci Cuidado Integrado

    Healthtech · Clinic management

    Running in production

    Clinical management for an integrated care clinic: appointments, patient records and evolution tracking for the professionals who use it every day.

    Flask · PostgreSQL · Bootstrap · JavaScript

How I build

Seven disciplines, one builder, nothing handed off. Every one of them has shipped in a product above.

  1. Architecture

    Every build starts with the domain, not the framework. I map the business into modules, tenants and permissions, then set the boundaries that keep a codebase changeable past 80,000 lines.

    Tools: Clean Architecture · Multi-tenant SaaS · RBAC · Domain modelling

    34modules in one multi-tenant platformEvoSolar Franquias · 83k+ lines

  2. Data

    PostgreSQL as the source of truth, Redis where speed matters, and access rules designed into the model from the first migration, so permissions never become an afterthought.

    Tools: PostgreSQL · Redis · MySQL · SQLAlchemy · asyncpg

    6role levels, from admin to doctor and coachBR1 Sports Academy

  3. API & workers

    Async FastAPI services, plus background workers that keep going when nobody is watching: schedules, retries, webhooks and real-time chat.

    Tools: FastAPI · Celery · WebSockets · Flask · PHP 8.3 · Slim

    38API endpoints across 15 service domainsZelo App

  4. Intelligence

    AI wired in as a system component, not bolted on as a demo: multi-provider LLM chains with automatic fallback, OCR pipelines and agents that call real tools.

    Tools: OpenAI · Claude · Gemini · Tool-use agents · OCR · Prompt caching

    3LLM providers in production, with automatic fallbackVivi AI · Zelo App

  5. Interface

    Web and mobile front ends people use every day: React and Next.js on the web, React Native and Expo on phones, Angular and Ionic where the platform already lives.

    Tools: React · Next.js · TypeScript · React Native · Expo · Angular · Ionic

    2client apps served by one AI backendVivi AI · Angular web and Ionic mobile

  6. Quality gate

    Nothing leaves without passing the gate: automated test suites, CI on every push, retries with backoff, and security reviews against OWASP.

    Tools: Test suites · GitHub Actions · OWASP · HMAC · Tenacity

    1,900+automated tests, 99.9% passingVivi AI

  7. Ship

    Containerised with Docker and deployed through CI to the cloud. Then the next product starts.

    Tools: Docker · GitHub Actions · AWS · Oracle Cloud · Cloudflare

    7products built and shipped end to endListed above

Track record

Now: founder of Zelo, full stack developer at Visol and Information Systems student at CEFET/RJ.

  1. 2026 – now

    Founder

    Zelo · medication-care healthtech

    Founded Zelo and build the product end to end: a FastAPI backend with 38 endpoints across 15 service domains, a React Native app on Expo, OCR that reads medicine boxes against the ANVISA catalogue, a three-provider LLM chain with fallback, and LGPD compliance.

    • FastAPI
    • React Native
    • Expo
    • PostgreSQL
    • Celery
    • LLMs

  2. 2025 – now

    Full Stack Developer

    Visol · solar-energy SaaS and CRM

    Intern from 2025 to Sep 2026, hired in Sep 2026

    Designed and shipped Vivi AI, the company's production assistant. Led the OWASP security hardening of the PHP core (SQL injection, IDOR, SSRF, webhook HMAC, OAuth CSRF) and integrated the franchise hub across the Angular CRM and the Ionic app. Day to day I also work with Rust and Redis.

    • Python
    • FastAPI
    • Rust
    • Redis
    • LLMs
    • PHP
    • Angular
    • Ionic

  3. 2024 – now

    Full Stack & SaaS Developer

    Freelance and independent products

    Solo-built multi-tenant SaaS across healthtech, solar energy, sports and education: architecture, backend, web, mobile, deploy and integrations with Google Ads, Meta Graph API, Firebase, OneSignal and ANVISA. Delivered Pecci Cuidado Integrado to a clinic, in production.

    • FastAPI
    • React
    • React Native
    • PostgreSQL
    • Multi-tenant

  4. 2025 – 2028

    B.Sc. Information Systems

    CEFET/RJ · Nova Friburgo

    In progress: systems architecture, databases, distributed computing and software engineering.

    • Information Systems

Open source

Tooling, experiments and reference architectures I keep in public.

All repositories on GitHub

Your product could be the next window here.

Open to new projects, full-time roles and collaborations, whether you need a whole product built from scratch or AI wired into systems you already run.

Email meDownload CV