Senior Full Stack Engineer · São Paulo, Brazil

Wenderson
Belko

Senior Full Stack Engineer | TypeScript · Node.js · NestJS · React · Next.js | AWS · Microservices · Payments & iGaming

6+ years building systems that have to stay up under real load — from financial platforms to mobile apps. I write the code and I answer the page when something breaks at 2 a.m.

Talk to me LinkedIn GitHub
6+years of experience
6companies
2020in the industry since
25+technologies

For recruiters

Looking for
Senior Full Stack · Senior Software Engineer
Work model
Remote (Brazil) or hybrid in São Paulo
Core stack
TypeScript · Node.js · NestJS · React · Next.js · AWS
Domain
Payments, digital wallets, iGaming, integrations

How I work

I am a full stack generalist: I handle the frontend and the backend, from the screen the user sees to the service that processes payments behind it. That is not about knowing a little of everything — it is about following a problem from start to finish without handing it off three times.

My specialty is critical financial systems: where a mistake means user money in the wrong place. Digital wallets, withdrawals and deposits, reconciliation, invoicing, identity verification. Systems where idempotency, audit logs and partial-failure handling are not an architect’s luxury — they are the baseline.

I like complex integrations, the kind nobody wants: badly documented APIs, external providers that answer differently from what they promise, flows that must reconcile two systems that disagree. That is where the work gets interesting.

And I cannot leave a problem open. It is a flaw and a strength at the same time: it makes me dig until I find the root cause — and stay up until I do.

  • Financial systems
  • Complex integrations
  • Scalable architecture
  • Cloud & DevOps
  • Mobile
  • Applied AI

Where I have solved these problems

Six companies in six years. I describe them by the type of system — each client’s name stays between me and them.

  1. Online betting & iGaming

    Currently

    Full stack development of a large-scale betting platform: player site, back office, digital wallet with balance, bonuses and history, withdrawal and deposit APIs, casino provider integration, identity verification and compliance. Cloud infrastructure with decoupled services and load testing.

    • React
    • NestJS
    • AWS
    • TypeScript
    • k6
    • PostgreSQL

  2. Healthcare & scheduling

    Recent projects

    End-to-end appointment scheduling systems with payment integration, invoicing for domestic and foreign clients, financial reconciliation and tax deduction calculation. Mobile version of the same product.

    • React
    • NestJS
    • React Native
    • RabbitMQ
    • PostgreSQL

  3. Logistics & compliance

    Previous experience

    Logistics management system built from scratch, including a compliance area with access management and user validation. Microservices architecture with containers and asynchronous messaging.

    • NestJS
    • AdonisJS
    • Docker
    • RabbitMQ
    • MongoDB

  4. Marketplace & referral program

    Previous experience

    Development on a high-volume cashback platform, on the team responsible for the referral program. Frontend A/B testing and service-to-service communication over gRPC.

    • React
    • Node.js
    • Python
    • gRPC
    • Firebase

  5. Automation & desktop

    Personal projects

    Management and execution system for Python automation bots, with a desktop interface, server-side rendering and Clean Architecture.

    • Python
    • ElectronJS
    • Clean Architecture

  6. Early career

    2020 – 2021

    Started as an intern and became a full-time developer within six months, going on to lead the team technically. That is where I built the frontend and prototyping foundation I still use today.

    • React
    • TypeScript
    • Figma
    • HTML/CSS

What I master

01Frontend

  • React
  • Next.js
  • React Native
  • TypeScript
  • Angular
  • HTML5 / CSS3
  • Figma

02Backend

  • Node.js
  • NestJS
  • Express
  • AdonisJS
  • PHP
  • Python
  • gRPC
  • REST APIs

03Infra & DevOps

  • AWS
  • Docker
  • RabbitMQ
  • Microservices
  • k6
  • Jest
  • Git
  • Linux

04Databases

  • PostgreSQL
  • MongoDB
  • Redis
  • MySQL
  • Firebase
  • Oracle

05Integrations

  • Payment gateways
  • KYC / Compliance
  • E-invoicing
  • Withdrawal & deposit APIs
  • Casino providers

Projects & writing

Things running in production, repositories worth a click and technical notes.

All projects → Blog →
Project In production

Propaganda na TV: a TV da loja anunciando sozinha

SaaS em produção que transforma qualquer TV de loja em painel de anúncios: o lojista monta a playlist no celular, pareia a TV com um código e troca preços em segundos. Laravel 12, Livewire 4, Tailwind 4, assinaturas via Asaas (Pix, boleto e cartão) e player que funciona offline.

AI in my daily work

I have followed the field since the first rumors and tried each model as it came out, more out of curiosity than hype. Over time it stopped being an experiment and became part of how I work.

  • Claude
  • ChatGPT
  • Gemini
  • Cursor
  • + whatever comes next
A

As a tool

In my workflow, every day

  • Learning — get into a new technology in hours, not weeks
  • Unblocking — a second opinion right away
  • Review — another pair of eyes before the PR
  • Prototyping — validate an idea before writing it for real
  • Automation — mechanical work does not deserve my time
B

Built into the product

Inside the systems I build

  • LLM APIs — backend integration with cost and failure control
  • Vector DB & RAG — semantic search over the client’s data
  • Tool-using agents — multi-step tasks on their own
  • Workflow automation — triage and processing without intervention

MINDFUL USE Using it well also means knowing when not to. Generated code only goes into a project after it has been read, understood and tested — if I cannot explain what is there, it does not ship. AI speeds up people who already know what they want to build; it does not replace understanding the problem. Enthusiast, not evangelist.

Or ask from the command line

If you are in the field, you might prefer it this way.

belko@belko.com.br — /usr/bin/perfil TTY1

Want to work together?

For job opportunities and technical conversations, reach out directly. For software projects, the way in is through Belko Dev.

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