Financial software has a lower tolerance for mistakes than most other code. A rounding error of a fraction of a cent, repeated across millions of transactions, becomes a real discrepancy, and an unclear API can lead to a payment being sent twice. This module covers the backend skills you need before you start building anything that touches money.
You'll start with how to represent money in code, including why floating-point numbers give unexpected results and why finance teams use decimal types or whole minor units such as cents instead. Then you'll look at REST APIs: resources, HTTP methods, status codes, and the ideas of statelessness and idempotency that payment APIs depend on. Finally, you'll learn Git and GitHub, so every change to your code is tracked and reviewable.
Pick one language and stay with it for the course: Java, Python, Go, and Node.js are all common in fintech. Once you've finished this module, move on to Databases & Ledger Design.
Why adding 0.1 and 0.2 doesn't give exactly 0.3, how computers store numbers in base 2, and why currency should use a decimal type or whole units like cents.
How RESTful APIs are structured around resources, HTTP methods, and status codes, with a look at statelessness, idempotent actions, pagination, and versioning.
The basics of Git and GitHub: staging and committing, branching and merging, keeping secrets out with a .gitignore file, and contributing through pull requests.