OpenRouter Fusion API: Fable-like AI at Half the Cost

OpenRouter has launched Fusion, a new API that can match the performance of advanced AI models like Claude Fable 5, but at half the cost. This new system combines multiple AI models to answer a single prompt. Here's how it works: Fusion sends a prompt to several AI models simultaneously. A judge model then analyzes all the responses, noting agreements and contradictions. Finally, a synthesizer model crafts a single, accurate answer based on this analysis. OpenRouter states that three-quarters of Fusion's performance gain comes from this synthesis step. In tests, a budget-friendly Fusion panel outperformed solo models like GPT-5.5 and Claude Opus 4.8. It even came within 1% of Fable 5's score, costing roughly half as much. This is significant because Anthropic recently withdrew its Fable and Mythos models due to export controls. The bottom line: Fusion offers a powerful and more affordable alternative for AI users worldwide, especially now that some top-tier models are no longer available.