The final result looks cool (based on how they're shown on the original Blog post) and I may do something similar, but:

Why do people make tools like this and insist on using the GitHub api.

What does it give you that accessing a local repo wouldn't?

Highly inspired by Pete Corey's Elixir-based code poster creator, this project aims to simplify the creation of a code poster SVG using a source image file and a GitHub repository.