Nobody keeps the receipts for AI pricing, so I built the changelog

I got one surprise AI bill that woke me up and I went looking for a simple answer: what did this model actually cost on the day I ran it?

Turns out that is weirdly hard. Provider pricing pages change quietly with no changelog. The Wayback Machine is patchy. And the obvious shortcut, today's price times last month's tokens, is just wrong the moment a provider shifts rates mid-period.

Whilst building a couple of small tools that calculate AI usage costs bugs popped up and traced back to one thing: I could not reliably say what a given model cost on a given date. Estimations are easy, knowing is hard.

So I built

Browse it : : how much are all models on Jun 17th 2026?