---
title: Route through OpenRouter
description: Send model calls through OpenRouter on one key.
---
> ## Documentation Index
> Fetch the complete documentation index at: https://docs.reeval.ai/llms.txt
> Use this file to discover all available pages before exploring further.

`openrouter()` sends the model calls of the harnesses it serves through OpenRouter, on one key. The egress gateway swaps the key in only on OpenRouter's model paths at `openrouter.ai`, so the key never enters the sandbox.

## Credential

`openrouter()` reads `OPENROUTER_API_KEY` from the environment or the `.env.local` file. A run exits with code 2 when the variable is unset and a planned harness or model takes `openrouter()`.

For more information about the variable, see [`OPENROUTER_API_KEY`](/reference/environment-variables#openrouterapikey).

## Helper

`openrouter()` is exported from `{{ pkg }}/gateway`:

```ts title="reeval.config.ts"
import { defineConfig } from '{{ pkg }}'
import { direct, openrouter } from '{{ pkg }}/gateway'

export default defineConfig({
  gateway: [openrouter({ fallbacks: true }), direct()],
})
```

With `fallbacks: true`, reeval's own calls may fail over to another upstream provider. The harnesses' calls keep OpenRouter's own routing. For more information about the option, see [`fallbacks`](/reference/options#openrouter-options).

A harness `openrouter()` cannot serve takes the next gateway in the list. Each call records the upstream provider that served it, on the attempt's `upstreams` and the judgment's `upstream`.

For more information about combining gateways, see [Gateways](/configuration/gateways).

## Harnesses and models

For the harnesses `openrouter()` serves, and the ones that fall through to the next gateway, see [Harness support](/configuration/gateways#harness-support).

On `openrouter()`, a judge must be a decision model that OpenRouter answers on its Decisions API, such as `typesafe/jev-1.14`, and each call to any other judge model fails. Analysis, captures, and questions take language models, which `openrouter()` calls on OpenRouter's Chat Completions API.