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OpenRouter provides a unified API to access models from multiple providers including OpenAI, Anthropic, Google, Meta, and more. It’s an excellent choice for flexibility and model variety.

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Why Use OpenRouter?

  • Multiple Models: Access GPT-4, Claude, Gemini, Llama, and dozens of other models
  • Single API Key: One key for all models
  • Cost Effective: Pay only for what you use
  • No Subscriptions: No monthly fees required
  • Model Routing: Automatically route to the best available model

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Setup Steps

1

Get Your API Key

  1. Visit OpenRouter
  2. Sign up or log in to your account
  3. Navigate to the API Keys page
  4. Create a new API key
  5. Copy your API key (starts with sk-or-v1-...)
2

Configure Forge

Run the interactive login command:
forge provider login
Select OpenRouter from the list and paste your API key when prompted.
3

Select a Model

OpenRouter supports many models. Popular choices include:
  • anthropic/claude-sonnet-4-20250514 - Latest Claude Sonnet
  • openai/gpt-4o - GPT-4 Omni
  • google/gemini-2.5-pro - Gemini Pro
  • meta-llama/llama-3.3-70b-instruct - Llama 3.3
Set your default model in forge.yaml:
model: anthropic/claude-sonnet-4-20250514
4

Verify Connection

Start Forge and test your setup:
forge
Try a simple prompt:
> Hello! Can you confirm this is working?

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Available Models

OpenRouter provides access to hundreds of models. To see all available models: 
forge
# Then in the Forge session:
/model
Or visit the OpenRouter Models page.

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Configuration

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API Endpoint

  • Chat Completions: https://openrouter.ai/api/v1/chat/completions
  • Models List: https://openrouter.ai/api/v1/models

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Authentication

OpenRouter uses API key authentication via the Authorization header.

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Advanced Features

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Model Selection

You can switch between models at any time using the /model command: 
/model openai/gpt-4o

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Cost Tracking

OpenRouter provides detailed usage and cost information in your dashboard. You can:
  • Monitor spending in real-time
  • Set spending limits
  • View usage by model

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Troubleshooting

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Invalid API Key

If you see an authentication error:
  1. Verify your API key is correct
  2. Check that the key starts with sk-or-v1-
  3. Ensure you’ve added credits to your OpenRouter account

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Model Not Available

Some models require additional setup or credits:
  1. Check the OpenRouter Models page
  2. Ensure the model supports the features you need
  3. Verify you have sufficient credits

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Rate Limits

OpenRouter has rate limits that vary by model and plan:
  • Check your current limits in the dashboard
  • Consider upgrading your plan for higher limits
  • Implement retry logic for production use

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Deprecated: Environment Variable Setup

Using environment variables is deprecated. Please use forge provider login instead.
For backward compatibility, you can still use: 
# .env
OPENROUTER_API_KEY=sk-or-v1-your-api-key
This will be automatically migrated to file-based storage on first run.

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Next Steps

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