LLM Model Routing: How to Automatically Pick the Right AI Model for Each Task

Using one LLM for everything is like using a chainsaw to cut butter. It works, but you're overpaying massively. Model routing is the practice of automatically directing each AI request to the most cost-effective model that can handle it. Complex reasoning goes to Claude Opus. Simple edits go to DeepSeek. Structured extraction goes to GPT. Here's how to build it. The Cost Problem A typical AI coding pipeline without routing: All requests → Claude Sonnet 4.6 → $3/$15 per 1M tokens...