Auto Router

The Auto Router (openrouter/auto) automatically selects the best model for your prompt, powered by NotDiamond.

Overview

Instead of manually choosing a model, let the Auto Router analyze your prompt and select the optimal model from a curated set of high-quality options. The router considers factors like prompt complexity, task type, and model capabilities.

Usage

Set your model to openrouter/auto:

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import { OpenRouter } from '@openrouter/sdk';
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const openRouter = new OpenRouter({
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  apiKey: '<OPENROUTER_API_KEY>',
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});
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const completion = await openRouter.chat.send({
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  model: 'openrouter/auto',
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  messages: [
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    {
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      role: 'user',
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      content: 'Explain quantum entanglement in simple terms',
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    },
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  ],
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});
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console.log(completion.choices[0].message.content);
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// Check which model was selected
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console.log('Model used:', completion.model);

Response

The response includes the model field showing which model was actually used:

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{
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  "id": "gen-...",
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  "model": "anthropic/claude-sonnet-4.5",  // The model that was selected
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  "choices": [
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    {
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      "message": {
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        "role": "assistant",
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        "content": "..."
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      }
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    }
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  ],
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  "usage": {
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    "prompt_tokens": 15,
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    "completion_tokens": 150,
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    "total_tokens": 165
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  }
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}

How It Works

1. Prompt Analysis: Your prompt is analyzed by NotDiamond’s routing system
2. Model Selection: The optimal model is selected based on the task requirements
3. Request Forwarding: Your request is forwarded to the selected model
4. Response Tracking: The response includes metadata showing which model was used

Supported Models

The Auto Router selects from a curated set of high-quality models including:

• Claude Sonnet 4.5 (anthropic/claude-sonnet-4.5)
• Claude Opus 4.5 (anthropic/claude-opus-4.5)
• GPT-5.1 (openai/gpt-5.1)
• Gemini 3.1 Pro (google/gemini-3.1-pro-preview)
• DeepSeek 3.2 (deepseek/deepseek-v3.2)
• And other top-performing models

The exact model pool may be updated as new models become available.

Configuring Allowed Models

You can restrict which models the Auto Router can select from using the plugins parameter. This is useful when you want to limit routing to specific providers or model families.

Via API Request

Use wildcard patterns to filter models. For example, anthropic/* matches all Anthropic models:

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const completion = await openRouter.chat.send({
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  model: 'openrouter/auto',
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  messages: [
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    {
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      role: 'user',
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      content: 'Explain quantum entanglement',
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    },
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  ],
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  plugins: [
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    {
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      id: 'auto-router',
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      allowed_models: ['anthropic/*', 'openai/gpt-5.1'],
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    },
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  ],
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});

Via Settings UI

You can also configure default allowed models in your Plugin Settings:

1. Navigate to Settings > Plugins
2. Find Auto Router and click the configure button
3. Enter model patterns (one per line)
4. Save your settings

These defaults apply to all your API requests unless overridden per-request.

Pattern Syntax

When no patterns are configured, the Auto Router uses all supported models.

Pricing

You pay the standard rate for whichever model is selected. There is no additional fee for using the Auto Router.

Use Cases

• General-purpose applications: When you don’t know what types of prompts users will send
• Cost optimization: Let the router choose efficient models for simpler tasks
• Quality optimization: Ensure complex prompts get routed to capable models
• Experimentation: Discover which models work best for your use case

Limitations

• The router requires messages format (not prompt)
• Streaming is supported
• All standard OpenRouter features (tool calling, etc.) work with the selected model

Related

• Body Builder - Generate multiple parallel API requests
• Latest Model Resolution - Always target the newest version of a model family
• Model Fallbacks - Configure fallback models
• Provider Selection - Control which providers are used