> ## Documentation Index
> Fetch the complete documentation index at: https://apixo.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# OpenAI Responses API

> Use OpenAI Responses-compatible requests through APIXO

Use APIXO as an OpenAI Responses-compatible API gateway. Keep the Responses API request format, replace the base URL, and use your APIXO API key.

## What to change

| Setting        | APIXO value                                                                |
| -------------- | -------------------------------------------------------------------------- |
| SDK Base URL   | `https://llm.apixo.ai/v1`                                                  |
| Endpoint       | `POST /responses`                                                          |
| Request URL    | `https://llm.apixo.ai/v1/responses`                                        |
| API key        | `APIXO_API_KEY` from [APIXO API Keys](https://apixo.ai/dashboard/api-keys) |
| API key header | `Authorization: Bearer $APIXO_API_KEY`                                     |
| Model location | Request body `model`                                                       |

## Quickstart

```bash theme={null}
export APIXO_API_KEY="your_apixo_api_key"
```

```bash theme={null}
curl -X POST "https://llm.apixo.ai/v1/responses" \
  -H "Authorization: Bearer $APIXO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.4",
    "input": "Say hello in one sentence."
  }'
```

## Streaming

```bash theme={null}
curl -N -X POST "https://llm.apixo.ai/v1/responses" \
  -H "Authorization: Bearer $APIXO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.4",
    "stream": true,
    "input": "Write a short changelog summary."
  }'
```

## SDK example

Use the OpenAI SDK with APIXO's Responses-compatible base URL.

```javascript theme={null}
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.APIXO_API_KEY,
  baseURL: "https://llm.apixo.ai/v1"
});

const response = await client.responses.create({
  model: "gpt-5.4",
  input: "Say hello in one sentence."
});

console.log(response.output_text);
```

## Supported OpenAI models

* `gpt-5.4`
* `gpt-5.4-pro`
* `gpt-5.4-mini`
* `gpt-5.4-nano`
* `gpt-5.2`
* `gpt-5.1`

## Troubleshooting

* `401`: missing or invalid API key
* `400`: invalid Responses API request body or unsupported model id
* `429`: rate limit or temporary capacity limit
* `502` / `504`: upstream provider error or timeout

Retry `429`, `502`, and `504` with backoff. Fix `400` and `401` before retrying.

## Related

* [LLM Gateway Overview](/docs/llm)
* [Supported Models](/docs/llm/supported-models)
* [LLM Authentication](/docs/llm/authentication)
* [LLM Streaming](/docs/llm/streaming)
* [LLM Errors and Retry](/docs/llm/errors-retry)
* [Pricing](https://apixo.ai/pricing)