LLM Gateway

The Onyx LLM Gateway gives applications one endpoint for the language models your organization has configured in Onyx. Requests use your Onyx identity, so model access and usage attribution stay in one place. Use the gateway when you want an application, automation, or coding tool to use organization-approved models without storing a separate provider key.

The LLM Gateway is available with Onyx Enterprise. An administrator must configure at least one visible language model before it can serve requests.

What the gateway provides

An OpenAI-compatible Chat Completions endpoint.
An OpenAI Responses endpoint.
An Anthropic Messages endpoint and token-count endpoint.
The models that your Onyx identity can access.
Usage attribution through the existing Onyx usage views.
The same model access controls and token limits that apply in Onyx.

The gateway does not replace your model-provider configuration. An administrator still configures providers and decides which models are visible in Language Models.

Onyx Admin Panel showing available language-model providers

Before you begin

You need all of the following:

An Onyx administrator has configured a language model and made it visible.
Your Onyx account has access to that model.
A Personal Access Token (PAT) with the LLM Gateway scope.

Create a Personal Access Token from Settings > Accounts & Access. Choose Limited access and select LLM Gateway. Treat the token as a password. Onyx shows it only once.

Use a scoped PAT for an application or local development. It limits the token to gateway requests while preserving the model access of the user who created it.

Gateway address

For a standard Onyx deployment, use:

https://your-onyx-domain.com/api/gateway/v1

Self-hosted deployments can expose the API at a different public path. Use the public API address for your deployment, followed by /gateway/v1. Every request uses a Bearer token:

export ONYX_GATEWAY_URL="https://your-onyx-domain.com/api/gateway/v1"
export ONYX_GATEWAY_API_KEY="onyx_pat_..."

Find an available model

The easiest way to find a model ID is in Settings > LLM Gateway. The section appears only when at least one model is visible and accessible to your account. Open a provider, then copy the ID beside the model that you want to use. The copied value already has the required format:

Onyx LLM Gateway settings with an expanded provider and model IDs

<provider-id>/<model-name>

For example, 12/gpt-5-mini means:

12 is the Onyx ID for the configured provider.
gpt-5-mini is the model name configured for that provider.

Use the copied value exactly as the model value in your client. Do not replace the provider ID with the provider name. Use Settings to find a model ID for each client configuration.

OpenAI Chat Completions

Point OpenAI-compatible clients at the gateway URL. This example uses the official OpenAI JavaScript SDK.

TypeScript

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.ONYX_GATEWAY_API_KEY,
  baseURL: process.env.ONYX_GATEWAY_URL,
});

const completion = await client.chat.completions.create({
  model: "12/gpt-5-mini",
  messages: [{ role: "user", content: "Write a one-line release note." }],
});

console.log(completion.choices[0].message.content);

The same request with stream: true uses server-sent events.

OpenAI Responses

The gateway also supports the OpenAI Responses API. Use the same base URL and model ID.

TypeScript

const response = await client.responses.create({
  model: "12/gpt-5-mini",
  input: "Summarize the purpose of this service in one sentence.",
});

console.log(response.output_text);

Gateway responses are stateless. Send the context that a later turn needs; do not rely on a previous response ID being stored by Onyx.

Anthropic Messages

For Anthropic-compatible clients, send requests to the gateway’s messages endpoint with the same Bearer token and model ID.

curl "$ONYX_GATEWAY_URL/messages" \
  -H "Authorization: Bearer $ONYX_GATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "18/claude-haiku-4-5",
    "max_tokens": 256,
    "messages": [
      {"role": "user", "content": "Reply with one friendly greeting."}
    ]
  }'

To estimate the input tokens for an Anthropic Messages request, send the same request shape to POST /messages/count_tokens.

Use with coding agents

Use the gateway with Claude Code or Codex to give coding-agent requests the same model access controls, usage attribution, and token limits as other gateway traffic.

Claude Code

Set the gateway’s parent endpoint as the Anthropic base URL, then use a Claude model ID from Settings:

export ANTHROPIC_BASE_URL="https://your-onyx-domain.com/api/gateway"
export ANTHROPIC_AUTH_TOKEN="$ONYX_GATEWAY_API_KEY"
export ANTHROPIC_MODEL="18/claude-haiku-4-5"
export ANTHROPIC_SMALL_FAST_MODEL="18/claude-haiku-4-5"

claude

Claude Code appends /v1/messages, which resolves to the gateway’s Anthropic Messages endpoint. Use a model ID from your own Settings page. Provider IDs differ by deployment.

Codex

Create a Codex profile at ~/.codex/onyx.config.toml:

model = "12/gpt-5-mini"
model_provider = "onyx_gateway"

[model_providers.onyx_gateway]
name = "Onyx Gateway"
base_url = "https://your-onyx-domain.com/api/gateway/v1"
wire_api = "responses"
env_key = "ONYX_GATEWAY_API_KEY"

Then export the PAT and start Codex with that profile:

export ONYX_GATEWAY_API_KEY="onyx_pat_..."
codex -p onyx

The configured model must be an OpenAI-compatible model ID from Settings.

OpenCode

Add the gateway as an OpenAI-compatible provider in your project’s opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "model": "onyx_gateway/12/gpt-5-mini",
  "provider": {
    "onyx_gateway": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "Onyx Gateway",
      "options": {
        "baseURL": "https://your-onyx-domain.com/api/gateway/v1",
        "apiKey": "{env:ONYX_GATEWAY_API_KEY}"
      },
      "models": {
        "12/gpt-5-mini": {
          "name": "GPT-5 mini via Onyx"
        }
      }
    }
  }
}

Export a PAT before starting OpenCode:

export ONYX_GATEWAY_API_KEY="onyx_pat_..."
opencode

The @ai-sdk/openai-compatible provider uses the gateway’s Chat Completions endpoint. Replace the example model with one from your Gateway Settings.

Usage and limits

Gateway requests use the calling user’s Onyx permissions. If the user loses access to a model, the gateway no longer exposes or accepts that model for the user. Administrators can review token use and estimated model cost in Admin Panel

Usage. They can also apply global, group, or user token limits there. Those limits apply before the gateway sends a generation request to a model provider.

Onyx Admin Panel controls for global, user, and group spending limits

Common errors

Error	What to check
`401` or `403`	Use a valid PAT with the LLM Gateway scope. Check that the user still has model access.
Model not found	Copy the model ID again from Gateway Settings. The provider ID is part of the identifier.
Rate limited	Ask an administrator to review the user, group, or workspace token limit.
Model unavailable	Ask an administrator to configure the provider or make the model visible in Language Models.

Getting Started

Core Features

Onyx Anywhere

Miscellaneous

What the gateway provides

Before you begin

Gateway address

Find an available model

OpenAI Chat Completions

OpenAI Responses

Anthropic Messages

Use with coding agents

Claude Code

Codex

OpenCode

Usage and limits

Common errors

Next steps

Configure language models

Create a Personal Access Token

​What the gateway provides

​Before you begin

​Gateway address

​Find an available model

​OpenAI Chat Completions

​OpenAI Responses

​Anthropic Messages

​Use with coding agents

​Claude Code

​Codex

​OpenCode

​Usage and limits

​Common errors

​Next steps

Configure language models

Create a Personal Access Token

What the gateway provides

Before you begin

Gateway address

Find an available model

OpenAI Chat Completions

OpenAI Responses

Anthropic Messages

Use with coding agents

Claude Code

Codex

OpenCode

Usage and limits

Common errors

Next steps