Passthrough - ModRouter

Overview

Passthrough endpoints keep the provider-native path and body instead of converting through an SDK-specific integration route. ModRouter still applies provider configuration, key selection, logging, governance, and plugin hooks where applicable. Use passthrough when:

the provider endpoint is not implemented by a ModRouter integration route,
you need provider-specific request fields exactly as-is,
you want ModRouter provider key management without rewriting the request body.

Endpoints

Provider family	Passthrough base URL
OpenAI	`/openai_passthrough`
Anthropic	`/anthropic_passthrough`
Azure OpenAI	`/azure_passthrough`
Google GenAI	`/genai_passthrough`

OpenAI Passthrough

curl -X POST "https://api.modrouter.online/openai_passthrough/v1/chat/completions" \
  -H "Authorization: Bearer ${MODROUTER_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o-mini",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Anthropic Passthrough

curl -X POST "https://api.modrouter.online/anthropic_passthrough/v1/messages" \
  -H "Authorization: Bearer ${MODROUTER_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 256,
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Azure Passthrough

curl -X POST "https://api.modrouter.online/azure_passthrough/openai/deployments/gpt-4o/chat/completions?api-version=2025-04-01-preview" \
  -H "Authorization: Bearer ${MODROUTER_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [{"role": "user", "content": "Hello"}]
  }'

ModRouter sources Azure auth details from the configured Azure provider key. Do not rely on client-supplied Azure api-key headers for upstream auth.

GenAI Passthrough

curl -X POST "https://api.modrouter.online/genai_passthrough/v1beta/models/gemini-2.5-flash:generateContent" \
  -H "Authorization: Bearer ${MODROUTER_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [{"parts": [{"text": "Hello"}]}]
  }'

Integration vs Passthrough

Prefer integration routes when ModRouter implements the endpoint you need. They return SDK-compatible response shapes and normalize provider behavior. Use passthrough when you intentionally need the provider-native API surface.

​Overview

​Endpoints

​OpenAI Passthrough

​Anthropic Passthrough

​Azure Passthrough

​GenAI Passthrough

​Integration vs Passthrough