I Spent $50 on LLM API Calls. Then Optimized to $0.

I Spent $50 on LLM API Calls. Then Optimized to $0. The real cost of AI features isn't the subscription - it's the prompts you haven't optimized yet. The $50 Month Two months ago, my OpenAI API bill hit $50. For a side project used by maybe 100 people. The features I was using weren't complex: User name extraction Email subject generation Simple categorization I was calling GPT-4o mini for everything because it was "cheap enough." But it added up. What I Changed 1. Better Prompt Engineering Same model, better prompts. A well-structured prompt with examples often matches a expensive model.