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When you send a request to https://gateway.ngrok.ai, the model field tells the AI Gateway which model to call. Use a model ID when you want the gateway to resolve the provider from the model catalog. Use provider:model when you want to choose the provider yourself.

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Use a model ID

Use a model ID when you know which model you want to call and don’t need to force a specific provider.
The gateway looks up gpt-4o in the model catalog, selects the matching provider, and routes the request upstream.

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Route to a specific provider

Use provider:model when you want predictable routing or need to avoid ambiguity between model names.
In this example:
  • openai is the provider ID.
  • gpt-4o is the model ID.
Use this format when you have more than one provider configured, want to call a custom provider, or want the request to go to one specific upstream.

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Use a custom provider model

Custom providers use the same provider:model format. In this example, my-ollama is your custom provider ID and llama3.2 is the model ID configured on that provider.

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Check model capabilities

Before choosing a model, check the model catalog for:

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Keep access rules in mind

The request can only use providers and models allowed by the access key configuration assigned to the access key. If you need to limit what a client can call, see Restrict providers and models.

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Next steps