Passthrough API

Overview

The passthrough API is in beta. Use it when you need a provider-native API shape, and prefer the OpenAI-compatible /v1 routes when you need the most stable GoModel interface.

The passthrough API proxies provider-native requests through GoModel without translating the request or response body. Use it when a client library expects a provider’s native API instead of the OpenAI-compatible API. For example, the Anthropic SDK sends requests to /v1/messages, so you can point it at GoModel’s Anthropic passthrough base URL:

http://localhost:8080/p/anthropic

The SDK sends:

POST /p/anthropic/v1/messages

GoModel normalizes the optional v1 segment and forwards the request upstream as Anthropic’s native:

POST /messages

How it works

Passthrough routes use this shape:

/p/{provider}/{endpoint}

For Anthropic, these two paths map to the same upstream endpoint when ALLOW_PASSTHROUGH_V1_ALIAS=true, which is the default:

/p/anthropic/messages
/p/anthropic/v1/messages

GoModel handles gateway authentication first. If GOMODEL_MASTER_KEY or managed auth keys are enabled, the client must send a GoModel bearer token:

Authorization: Bearer change-me

GoModel strips client Authorization and X-Api-Key headers before forwarding the request, then applies the upstream provider credential configured on the server. For Anthropic, GoModel uses its configured ANTHROPIC_API_KEY. Because passthrough is provider-native, the response is also provider-native. For Anthropic messages, the response uses Anthropic’s message schema, not an OpenAI chat completion schema. When usage tracking is enabled, successful passthrough inference responses are recorded: token counts are read from SSE usage events on streaming responses and from the usage member of JSON responses, so costs and budgets account for passthrough traffic like any other route.

Anthropic SDK example

Set the Anthropic SDK base URL to GoModel’s Anthropic passthrough route. Use the GoModel token as Anthropic SDK bearer auth.

import os
from anthropic import Anthropic

client = Anthropic(
    base_url="http://localhost:8080/p/anthropic",
    auth_token=os.environ["GOMODEL_MASTER_KEY"],
)

message = client.messages.create(
    model="claude-3-haiku-20240307",
    max_tokens=16,
    messages=[
        {
            "role": "user",
            "content": "Reply with exactly ok",
        }
    ],
)

print(message.content[0].text)

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  baseURL: "http://localhost:8080/p/anthropic",
  authToken: process.env.GOMODEL_MASTER_KEY,
});

const message = await client.messages.create({
  model: "claude-3-haiku-20240307",
  max_tokens: 16,
  messages: [
    {
      role: "user",
      content: "Reply with exactly ok",
    },
  ],
});

console.log(message.content[0].text);

If your gateway does not require authentication, use a dummy SDK API key such as not-needed instead of auth_token or authToken. GoModel strips X-Api-Key from passthrough requests before forwarding them upstream.

Current limitations

Passthrough is intentionally narrow while the API is in beta.

openai, anthropic, openrouter, kilo, zai, sglang, vllm, llamacpp, llmd, deepseek, edenai, and jev are enabled by default.
Chutes supports passthrough but requires explicit operator opt-in because passthrough can forward provider-native routes that do not identify a model. Add chutes to ENABLED_PASSTHROUGH_PROVIDERS only when you intend to expose that surface.
GoModel does not translate passthrough request bodies or response bodies.
The model a JSON passthrough body names is checked against the caller’s model allowlist regardless of body size, up to the configured body limit; a larger body is refused with the limit’s own error. A body that repeats the top-level model field is rejected, since the upstream would decide which one wins.
Provider-native error bodies and status codes are proxied instead of converted into OpenAI-compatible responses.
Features that depend on OpenAI-compatible request or response shapes may not apply to passthrough traffic in the same way as /v1 traffic.

Passthrough routes are enabled by default:

ENABLE_PASSTHROUGH_ROUTES=true
ALLOW_PASSTHROUGH_V1_ALIAS=true
ENABLED_PASSTHROUGH_PROVIDERS=openai,anthropic,openrouter,kilo,zai,sglang,vllm,llamacpp,llmd,deepseek,edenai,jev

Set ENABLED_PASSTHROUGH_PROVIDERS to the provider types you want to expose.

Getting Started

Features

Pro features

MCP Proxy

Advanced

About

Passthrough API

Overview

How it works

Anthropic SDK example

Current limitations

​Overview

​How it works

​Anthropic SDK example

​Current limitations

​Related environment variables

Overview

How it works

Anthropic SDK example

Current limitations

Related environment variables