Banking Challenges ​

Ever wondered how a Pix transfer actually works under the hood?

Not the pretty app interface. The ugly part. The massive XMLs, binary protocols, key directories, nightly reconciliations.

This project is a deep dive into that. 14 technical challenges simulating real Brazilian financial market problems.

Why it exists ​

Each challenge is a miniature of a real system. SPI, DICT, ISO 8583, Open Finance — these all exist in production and move billions daily.

The idea is simple: if you understand how these systems work internally, you can build anything in fintech.

What you'll find ​

• 11 backend services — each solving a specific problem
• 2 Go services — SPI and DICT reimplemented for performance
• 2 frontend apps — KYC and landing page with design system
• 4 databases — MongoDB, PostgreSQL, Redis, MinIO
• Full infra — Docker, Turborepo, CI/CD, Kubernetes
• Living docs — VitePress with i18n, Mermaid, built-in search

How to use ​

Each challenge is independent. You can run just the SPI Simulator or spin everything up at once.

git clone https://github.com/mateussiqueira/banking-stack.git
cd banking-stack
pnpm install
docker compose up -d
pnpm dev

Done. 13 services running. Each on its own port, each with its own database.

The philosophy ​

There's no right or wrong answer. There are trade-offs.

Node.js is great for prototyping. Go is great for production. GraphQL is good for complex queries. REST is good for simplicity. MongoDB is good for flexible data. PostgreSQL is good for structured data.

The goal isn't to teach you a language. It's to teach you how to think.