OpenRouter Responses

Interact with OpenRouter models using the OpenAI Responses API. OpenRouter's Responses API (currently in beta) provides OpenAI-compatible access to multiple AI models through a unified interface.

Requirements

Set the OPENROUTER_API_KEY environment variable:

1export OPENROUTER_API_KEY=your-api-key

Key Features

Unified Interface: Access multiple AI providers through a single API
Fallback Model Routing: Automatically try alternative models if the primary fails
Stateless API: Each request is independent (no server-side state persisted)
Reasoning Support: Enable reasoning for supported models

Parameters

Parameter	Type	Default	Description
`id`	`str`	`"openai/gpt-oss-20b"`	The ID of the OpenRouter model to use
`name`	`str`	`"OpenRouterResponses"`	The name of the model
`provider`	`str`	`"OpenRouter"`	The provider of the model
`api_key`	`Optional[str]`	`None`	The API key (defaults to `OPENROUTER_API_KEY` env var)
`base_url`	`str`	`"https://openrouter.ai/api/v1"`	The base URL for the OpenRouter API
`models`	`Optional[List[str]]`	`None`	List of fallback model IDs for automatic retry
`store`	`Optional[bool]`	`False`	Whether to store responses

Usage

Basic Usage

1from kern.agent import Agent
2from kern.models.openrouter import OpenRouterResponses
3
4agent = Agent(
5    model=OpenRouterResponses(id="openai/gpt-oss-20b"),
6    markdown=True,
7)
8
9agent.print_response("Share a 2 sentence horror story")

With Reasoning

1from kern.agent import Agent
2from kern.models.openrouter import OpenRouterResponses
3
4agent = Agent(
5    model=OpenRouterResponses(
6        id="openai/gpt-oss-20b",
7        reasoning={"enabled": True},
8    ),
9    markdown=True,
10)
11
12agent.print_response("Share a 2 sentence horror story")

Fallback Model Routing

If the primary model fails due to rate limits, timeouts, or unavailability, OpenRouter automatically tries the fallback models in order:

1from kern.agent import Agent
2from kern.models.openrouter import OpenRouterResponses
3
4agent = Agent(
5    model=OpenRouterResponses(
6        id="openai/gpt-oss-20b",
7        models=[
8            "openai/gpt-oss-20b",
9            "openai/gpt-4o",
10        ],
11    ),
12    markdown=True,
13)
14
15agent.print_response("Write a haiku about coding", stream=True)