OpenRouter's Model Fusion API
OpenRouter has released model fusion feature which they claim it performs in Fable-level intelligence at half the price
How does it work?
When you send a prompt to Fusion, we fan it out to a panel of models in parallel, each with web search and bash tools enabled.
A judge model reads every response and extracts the structure: consensus points, contradictions, partial coverage, unique insights, blind spots.
So the TLDR is in combines the context from all the models for the given prompt and synthesises the final answer.
How to use it?
Just add openrouter:fusion in tools like this
curl https://openrouter.ai/api/v1/chat/completions \
-X POST \
-H "Authorization: Bearer <OPENROUTER_API_KEY>" \
-H "Content-Type: application/json" \
-d '{
"model": "~anthropic/claude-opus-latest",
"messages": [
{
"role": "user",
"content": "Survey the strongest arguments for and against a multi-universe. Where do experts disagree?"
}
],
"tools": [
{ "type": "openrouter:fusion" }
]
}'
You can also customize the tools like this
{
"tools": [
{
"type": "openrouter:fusion",
"parameters": {
"analysis_models": [
"~google/gemini-flash-latest",
"deepseek/deepseek-v3.2",
"~moonshotai/kimi-latest"
],
"model": "~anthropic/claude-opus-latest"
}
}
]
}
And finally we’ll getting answer like this
{
"status": "ok",
"analysis": {
"consensus": ["Points all or most panel models agreed on"],
"contradictions": [
{ "topic": "...", "stances": [{ "model": "...", "stance": "..." }] }
],
"partial_coverage": [
{ "models": ["..."], "point": "Only some models covered this" }
],
"unique_insights": [
{ "model": "...", "insight": "Something only one model raised" }
],
"blind_spots": ["Topics no panel model addressed"]
},
"responses": [
{ "model": "anthropic/claude-opus-4.5", "content": "..." },
{ "model": "openai/gpt-4.1", "content": "..." },
{ "model": "google/gemini-2.5-pro", "content": "..." }
]
}