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# StepAudio 3 Chat

> Audio and text conversation model that reasons before answering, with function calling and JSON output.

![StepAudio 3 Chat](https://media.empiriolabs.ai/model-logos/stepaudio-3-chat.png)

[StepFun](/providers/stepfun) · Text Generation

`POST /v1/chat/completions`

Audio and text conversation model that reasons before answering, with function calling and JSON output.

## At a glance

| Field               | Value                                                                |
| ------------------- | -------------------------------------------------------------------- |
| Model id            | `stepaudio-3-chat`                                                   |
| Model release date  | 2026-09-09                                                           |
| Input modalities    | Text, Audio                                                          |
| Output modalities   | Text                                                                 |
| Context window      | 256K                                                                 |
| Weight precision    | -                                                                    |
| Max output tokens   | 131,072                                                              |
| Region              | International                                                        |
| Features            | reasoning, audio_in, function_calling, structured_output, multimodal |
| Native inference    | No                                                                   |
| New                 | Yes                                                                  |
| Structured output   | JSON Mode                                                            |
| Supported endpoints | `POST /v1/chat/completions`                                          |
| Alternate model ids | `stepaudio-3-chat-preview`, `stepfun/stepaudio-3-chat`               |

## Pricing

| Charge              | Spec                       | Rate    |
| ------------------- | -------------------------- | ------- |
| Input               | per 1M prompt tokens       | \$1.50  |
| Output              | per 1M generated tokens    | \$3.50  |
| Implicit cache read | per 1M cached input tokens | \$0.30  |
| Web Search (Linkup) | per call when invoked      | \$0.013 |

## Example request

```bash
curl https://api.empiriolabs.ai/v1/chat/completions \
  -H 'Authorization: Bearer $EMPIRIOLABS_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"model": "stepaudio-3-chat", "messages": [{"role":"user","content":"Hello"}]}'
```

## Parameters

| Parameter            | Type    | Required | Default     | Description                                                                                                                                                                                                                                                                         |
| -------------------- | ------- | -------- | ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `temperature`        | number  | no       | `0.5`       | Sampling temperature. · Range: 0 – 2                                                                                                                                                                                                                                                |
| `top_p`              | number  | no       | `0.9`       | Nucleus sampling probability mass. · Range: 0 – 1                                                                                                                                                                                                                                   |
| `max_tokens`         | integer | no       | `4096`      | Maximum output tokens. Reasoning tokens count toward this limit, so a small budget can be spent entirely on thinking and return an empty answer. Leave unset for a sensible default, or allow at least a few thousand tokens. · Range: 1 – 131072                                   |
| `stop`               | array   | no       | -           | Stop sequences.                                                                                                                                                                                                                                                                     |
| `frequency_penalty`  | number  | no       | `0`         | Penalty for repeated tokens. · Range: 0 – 1                                                                                                                                                                                                                                         |
| `modalities`         | array   | no       | `["text"]`  | Response modalities. Text output is currently exposed.                                                                                                                                                                                                                              |
| `response_format`    | object  | no       | -           | OpenAI-compatible response format. Use \{"type":"json_object"} for JSON object mode.                                                                                                                                                                                                |
| `reasoning_format`   | enum    | no       | `"general"` | Reasoning trace format returned by StepFun. · Allowed: `general`, `deepseek-style`                                                                                                                                                                                                  |
| `tools`              | array   | no       | -           | OpenAI-compatible function tools.                                                                                                                                                                                                                                                   |
| `tool_choice`        | string  | no       | -           | OpenAI-compatible tool choice.                                                                                                                                                                                                                                                      |
| `web_search_linkup`  | boolean | no       | false       | Optional web search powered by Linkup. When enabled, recent web sources are retrieved using your latest user message as the query and provided to the model as additional context. Adds \$0.013 per call when invoked on top of the model's normal token cost. Disabled by default. |
| `disable_formatting` | boolean | no       | false       | When enabled, the gateway will not append the "Sources" footer to assistant responses that used Linkup web search. Useful when the model output is piped to another system that expects no decoration.                                                                              |

## Notes

Accepts text and audio input and replies with text. The model reasons before answering and returns its reasoning alongside the answer, and those reasoning tokens bill as output tokens. Because reasoning consumes the output budget, a small max_tokens can be spent entirely on thinking and return an empty answer; leave max_tokens unset for a sensible default, or allow at least a few thousand tokens. Function calling and JSON object output are supported. Linkup web search is available for text prompts. This model is in preview and its capabilities may change.

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*Machine-readable schema:* `GET https://api.empiriolabs.ai/v1/models/stepaudio-3-chat`.