OpenRouter Fusion: How It Works and When to Use It

Fusion is our compound model. It takes one prompt and turns it into a short debate among several models. We send your prompt to a panel of expert models at once, and a judge compares every response so the calling model can write a single final answer. With Fusion, you trade some speed and tokens for quality. This page covers what Fusion does, what it costs, when it beats a single model, and when it doesn’t. What Fusion does. It gives a model access to a multi-model deliberation tool. A panel answers in parallel, a judge maps agreement and disagreement, and the calling model writes the final response. What it costs. An invoked Fusion call adds panel and judge completions. The default three-model panel costs roughly four to five times as much as one completion on the same prompt and often takes two to three times longer. When to use it. Use Fusion as a selective escalation path for complex research, expert critique, and decisions where an…