Full Stack Engineer · Joinville, BR

Luiz Fernando Witt

I ship scalable B2B SaaS

Product-minded full stack engineer with end-to-end ownership — from architecture to production across React / TypeScript and Python / Node.

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About

01 — 04

I take ideas all the way to production — and own every layer in between.

I'm a full-stack engineer who does his best work at the intersection of product and engineering — where good UX meets clean, scalable code. I care about the details that never show up in a demo but decide whether a product holds up in production, and about the metrics that move a business rather than the ones that just look good in a commit.

Right now I'm at Carbon Free Brasil, where I led the migration of a legacy PHP monolith to modular FastAPI services and built the serverless pipelines behind real-time GHG calculations for 200+ enterprise clients — John Deere, Heineken, Coca-Cola, McDonald's. Before that I shipped financial tooling at a $4B+ wealth manager, and launched an AI-driven product from 0 to 1 as a founding engineer.

Across a B2B SaaS, a wealth-management firm, and an early-stage startup, I've learned to build products that are both well-crafted and genuinely useful — and, just as importantly, to actually ship them.

Outside of code you'll usually find me with a guitar in hand — acoustic or electric — chasing a riff instead of a bug.

Selected work

Where I've shipped

Nov 2024 — Present

Carbon Free Brasil

Full Stack Engineer

B2B SaaS · 200+ enterprise clients (John Deere, Heineken, Coca-Cola, McDonald’s) · $1.5M+ ARR

Spearheaded the migration from a legacy PHP monolith to modular FastAPI microservices with automated testing — 80% fewer bugs, 60% faster response times, 90% shorter delivery cycles.
Architected an event-driven serverless pipeline (AWS Lambda / Python) for real-time GHG calculations and PDF generation — cut document processing from 9s to under 1s and manual effort by 90%.
Automated complex data ingestion for enterprise integrations — cut manual input from 45 min to under 5 min per session and eliminated recurring data-entry errors.

FastAPI
Python
AWS Lambda
React

Sep 2023 — Nov 2024

Manchester Investimentos

Frontend Developer

Wealth management · $4B+ AUC · 200+ advisors · internal CRM

Unblocked $1M+ in monthly portfolio simulations and eliminated reconciliation errors by optimizing financial processing engines and real-time simulators (Node.js, React).
Architected a ~70 MAU partner portal with automated PIX payments (Node.js, Next.js, AWS) processing $100K+ monthly, saving ~20 hours/month for finance.
Built a high-performance frontend architecture and shared component library, doubling delivery speed and adding Playwright E2E testing for a 14K+ client base.

React
Next.js
Node.js
Playwright

Jan 2023 — Aug 2023

Lize

Frontend Developer — Founding Engineer

Early-stage B2B SaaS · AI social-media publishing · ~2,000 MAU (ceased ops late 2023)

Launched the MVP from 0 to 1 as founding engineer, implementing an AI-driven content engine (Vue.js, Django).
Built an auto-pilot Instagram publishing feature via the Facebook API, delivering personalized scheduled content for 200+ users.
Designed an SVG-based brand template editor (Vue.js) letting the sales team generate client-branded assets in minutes instead of hours.

Vue.js
Django
Facebook API

Toolkit

The stack I reach for

Frontend

React
Next.js
TypeScript
Vue
Storybook
Playwright

Backend

FastAPI
Node.js
Express.js
Django

Architecture

REST APIs
Microservices
CI/CD
Clean Architecture
Test Automation

Cloud & DevOps

AWS (Lambda, EC2, S3)
Docker
Kubernetes
GitHub Actions
ArgoCD

Databases

PostgreSQL
MySQL
SQL Server

Monitoring

Sentry
PostHog
Metabase

Open channel

Let's build something that ships.

A project, a question, or just to swap notes on engineering — my inbox is open and I read everything.

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AWS Certified Cloud Practitioner