When I began my career in programming I remember reading Jeff Dean's "numbers every programmer should know", and getting inspired. Alas, it's been over a decade, and I never fully internalized all those numbers.

Until recently. I discovered Simon Eskildsen's talk [1] and github repo [2] on programmer napkin math, and decided to _actually_ internalize the numbers now.

So I made baserates.dev.

It's a spaced repetition program that teaches you the napkin math from Simon, enhanced with a few things from Jeff Dean's list (I thought stuff like L1 Cache reads) would be important too. I also included some nooby, but important things (like what how to pronounce the character μ, and a reminder on what is bigger: nano seconds, or micro seconds).

The app doesn't require auth. I use guest auth, so your progress is saved.

Most of the logic is vibe coded: I fed Claude all the links. I use InstantDB [^3] for the backend, mainly to support guest auth and saving progress. Most of my time spent on the project was just going through and making sure the numbers felt right.

Hope you enjoy it!

[1]: https://www.youtube.com/watch?v=IxkSlnrRFqc [2]: https://github.com/sirupsen/napkin-math