---
title: gpt-oss-20b · Cloudflare Workers AI docs
description: OpenAI’s open-weight models designed for powerful reasoning,
  agentic tasks, and versatile developer use cases – gpt-oss-20b is for lower
  latency, and local or specialized use-cases.
chatbotDeprioritize: false
source_url:
  html: https://developers.cloudflare.com/workers-ai/models/gpt-oss-20b/
  md: https://developers.cloudflare.com/workers-ai/models/gpt-oss-20b/index.md
---

![OpenAI logo](https://developers.cloudflare.com/_astro/openai.ChTKThcR.svg)

# gpt-oss-20b

Text Generation • OpenAI

@cf/openai/gpt-oss-20b

OpenAI’s open-weight models designed for powerful reasoning, agentic tasks, and versatile developer use cases – gpt-oss-20b is for lower latency, and local or specialized use-cases.

| Model Info | |
| - | - |
| Context Window[](https://developers.cloudflare.com/workers-ai/glossary/) | 128,000 tokens |
| Unit Pricing | $0.20 per M input tokens, $0.30 per M output tokens |

## Usage

Worker

```ts
export default {
  async fetch(request, env): Promise<Response> {
    const response = await env.AI.run('@cf/openai/gpt-oss-20b', {
      instructions: 'You are a concise assistant.',
      input: 'What is the origin of the phrase Hello, World?',
    });


    return Response.json(response);
  },
} satisfies ExportedHandler<Env>;
```

Python

```py
import os
import requests


ACCOUNT_ID = os.environ.get("CLOUDFLARE_ACCOUNT_ID")
AUTH_TOKEN = os.environ.get("CLOUDFLARE_AUTH_TOKEN")


prompt = "Tell me all about PEP-8"
response = requests.post(
  f"https://api.cloudflare.com/client/v4/accounts/{ACCOUNT_ID}/ai/v1/responses",
    headers={"Authorization": f"Bearer {AUTH_TOKEN}"},
    json={
      "model": "@cf/openai/gpt-oss-20b",
      "input": "Tell me all about PEP-8"
    }
)
result = response.json()
print(result)
```

curl

```sh
curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/responses   -H "Content-Type: application/json"   -H "Authorization: Bearer $CLOUDFLARE_AUTH_TOKEN"   -d '{
    "model": "@cf/openai/gpt-oss-20b",
    "input": "What are the benefits of open-source models?"
  }'
```

## Parameters

\* indicates a required field

### Input

* `input` required

  * `0` string

    Responses API Input messages. Refer to OpenAI Responses API docs to learn more about supported content types

  * `1` array

    Responses API Input messages. Refer to OpenAI Responses API docs to learn more about supported content types

* `reasoning` object

  * `effort` string

    Constrains effort on reasoning for reasoning models. Currently supported values are low, medium, and high. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response.

  * `summary` string

    A summary of the reasoning performed by the model. This can be useful for debugging and understanding the model's reasoning process. One of auto, concise, or detailed.

### Output

* `0` object

* `1` string

## API Schemas

The following schemas are based on JSON Schema

* Input

  ```json
  {
      "type": "object",
      "title": "GPT_OSS_Responses",
      "properties": {
          "input": {
              "anyOf": [
                  {
                      "type": "string"
                  },
                  {
                      "items": {},
                      "type": "array"
                  }
              ],
              "description": "Responses API Input messages. Refer to OpenAI Responses API docs to learn more about supported content types",
              "title": "Input"
          },
          "reasoning": {
              "type": "object",
              "properties": {
                  "effort": {
                      "type": "string",
                      "description": "Constrains effort on reasoning for reasoning models. Currently supported values are low, medium, and high. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response.",
                      "enum": [
                          "low",
                          "medium",
                          "high"
                      ]
                  },
                  "summary": {
                      "type": "string",
                      "description": "A summary of the reasoning performed by the model. This can be useful for debugging and understanding the model's reasoning process. One of auto, concise, or detailed.",
                      "enum": [
                          "auto",
                          "concise",
                          "detailed"
                      ]
                  }
              }
          }
      },
      "required": [
          "input"
      ]
  }
  ```

* Output

  ```json
  {
      "oneOf": [
          {
              "type": "object",
              "contentType": "application/json"
          },
          {
              "type": "string",
              "contentType": "text/event-stream",
              "format": "binary"
          }
      ]
  }
  ```
