I've been shipping AI features for the past year. Last month I hit a wall — my API bill crossed $300 and I had no idea where it was going.

So I did what any developer would: I built a cost tracker. Here's what 30 days of data taught me.

The Setup

I built a lightweight middleware that logged every API call: model used, token count, cost, and task type.

# Cost-tracking middleware for OpenAI-compatible APIs