Azure Model Router

Overview

Azure model router is an Azure OpenAI deployment family that automatically picks the best underlying model for a request. Bifrost’s native Azure provider supports model-router deployments for Chat Completions today. The Responses API is not yet exposed for model-router deployments through the native Azure provider. Until that lands, you can reach model-router’s Responses endpoint directly through your Azure AI Foundry project by configuring Azure Foundry as a custom provider, as described below.

This page covers model-router specifically. For general endpoint setup, authentication, aliases, and deployment configuration on the native Azure provider, see the main Azure provider guide.

Supported operations

Operation	Support	Notes
Chat Completions	✅	Native Azure provider or Azure Foundry custom provider
Chat Completions (stream)	✅	Native Azure provider or Azure Foundry custom provider
Responses API	⚠️	Requires adding Azure Foundry as a custom-provider
Responses API (stream)	⚠️	Requires adding Azure Foundry as a custom-provider

Adding Azure Foundry as a custom provider

Azure AI Foundry projects expose an OpenAI-Responses-API-shaped endpoint (*.ai.azure.com/api/projects/<project>/openai/v1/responses) that is distinct from the classic Azure OpenAI resource endpoint (*.openai.azure.com) used by the native Azure provider. You can reach it by creating a custom provider named e.g. azure-foundry with base_provider_type: "openai" and a full-URL request path override for the responses and responses_stream request types. A full URL in request_path_overrides bypasses base_url entirely, so requests go straight to your Azure AI Foundry project’s Responses endpoint.

Web UI
API
config.json

Go to Providers in the sidebar and click Add New Provider.
Name the provider azure-foundry (or similar).
Set Base Format to OpenAI.
Set Base URL to https://<your-resource>.ai.azure.com/openai.
Under Allowed Request Types, toggle on Responses and Responses Stream.
Click the settings icon next to each and enter the full Azure AI Foundry Responses URL in Custom Path or URL: https://<your-resource>.ai.azure.com/api/projects/<your-project>/openai/v1/responses
Add your Azure API key and save.

{
    "providers": {
        "azure-foundry": {
            "keys": [
                {
                    "name": "azure-foundry-key-1",
                    "value": "env.AZURE_API_KEY",
                    "models": ["*"],
                    "weight": 1.0
                }
            ],
            "network_config": {
                "base_url": "https://<your-resource>.ai.azure.com/openai"
            },
            "custom_provider_config": {
                "base_provider_type": "openai",
                "allowed_requests": {
                    "responses": true,
                    "responses_stream": true
                },
                "request_path_overrides": {
                    "responses": "https://<your-resource>.ai.azure.com/api/projects/<your-project>/openai/v1/responses",
                    "responses_stream": "https://<your-resource>.ai.azure.com/api/projects/<your-project>/openai/v1/responses"
                }
            }
        }
    }
}

Field	Type	Required	Description
`custom_provider_config.base_provider_type`	string	Yes	Must be `openai` so requests are shaped as OpenAI-compatible calls
`custom_provider_config.allowed_requests`	object	No	Restricts this provider to only the request types you enable
`custom_provider_config.request_path_overrides`	object	No	Full URL per request type; bypasses `network_config.base_url`
`network_config.base_url`	string	No	Used for any request type without a full-URL override

If you also want Chat Completions routed through this same custom provider instead of the native Azure provider, enable chat_completion / chat_completion_stream in allowed_requests and add matching entries in request_path_overrides. Otherwise, keep using the native Azure provider for Chat Completions and this custom provider only for Responses.

Usage

Call the Responses endpoint using the azure-foundry custom provider and your model-router deployment name:

curl -X POST http://localhost:8080/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "azure-foundry/model-router",
    "input": "Write a short haiku about gateways."
  }'

If you need to inspect provider-specific extra parameters, enable Send Back Raw Response. If you do not want those raw bytes persisted in logs, also set Store Raw Request/Response.

Limitations

Chat Completions for model-router deployments works through the native Azure provider; no extra configuration is needed.
Responses support for model-router requires the custom-provider workaround on this page until native support is added to the Azure provider.
This page does not change Azure authentication or endpoint setup for the native Azure provider - see the Azure provider guide for that.

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Azure Model Router

Overview

Supported operations

Adding Azure Foundry as a custom provider

Usage

Limitations

​Overview

​Supported operations

​Adding Azure Foundry as a custom provider

​Usage

​Limitations

​Related docs

Overview

Supported operations

Adding Azure Foundry as a custom provider

Usage

Limitations

Related docs