What Happened When I Got a Surprise $80 Claude Bill

It was a Tuesday morning. I opened my Anthropic dashboard to check usage like I do every few days, and there it was: $80.17. I stared at it for a solid ten seconds. I'm a solo dev. I build small Mac apps. I do not have $80 floating around for a single month of API calls that I barely remember making. How it happened Here's the thing — I wasn't even building anything big. I had been iterating on a feature for one of my apps, running Claude back and forth to refine some logic, and testing a few prompts. Normal stuff. The kind of session where you think "this'll be like $3." But I had left a loop running longer than I realized. A script that was calling Claude repeatedly for batch processing some test data. I forgot about it, went to bed, and woke up $80 lighter. No alerts. No cap. No warning. Just a bill. The problem nobody talks about LLM billing is genuinely different from anything else in software. With AWS, you at least get billing alarms. With Vercel, there are spending limits. But