How I Cut My LLM API Bill by 80% With a Simple Router

No fancy infrastructure. Just a 50-line Python function that picks the right model for the right query.

Last month my LLM API bill hit $340. This month: $67.

Same traffic. Same product. The only change was adding a simple router that stops sending every request to Claude Sonnet when GPT-4o mini can handle it just as well.

Here's exactly how it works.

The Problem

How I Cut My LLM API Bill by 80% With a Simple Router

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