# Black Forest Labs FLUX

Gateway FLUX native compatibility route, restricted to flux-3-image. Use the listed model protocols for other FLUX models.

## Endpoint and authentication

`POST https://api.tu-zi.com/flux/v1/flux-3-image`

Transport: json

Use an inference API key. Examples contain placeholders; read credentials from environment variables.

```http
Authorization: Bearer YOUR_API_KEY
Content-Type: application/json
```

## Body parameters

| Field | Type | Required | Description / constraints |
| --- | --- | --- | --- |
| prompt | string | Yes | Image generation prompt. |
| width | integer | No | Image width; the gateway requires a multiple of 32. Form initial value (not an upstream default): 1024 Range in this definition: 256 ~ 1440 |
| height | integer | No | Image height; the gateway requires a multiple of 32. Form initial value (not an upstream default): 1024 Range in this definition: 256 ~ 1440 |
| prompt_upsampling | boolean | No | Whether the upstream provider enhances the prompt. Form initial value (not an upstream default): false |
| seed | integer | No | Random seed. Range in this definition: 0 ~ 4294967295 |
| safety_tolerance | integer | No | Safety tolerance; 0 is the strictest setting. Form initial value (not an upstream default): 2 Range in this definition: 0 ~ 6 |
| output_format | string | No | Output image file format. Form initial value (not an upstream default): "jpeg" Values: "jpeg", "png", "webp" |

## Minimal request example

```json
{
  "prompt": "A white ceramic cup"
}
```

## Before running

Replace https://api.tu-zi.com with this site origin (do not append /v1 twice), and YOUR_MODEL with the exact marketplace model ID. Install requests for Python; use Node.js 20+ and save JavaScript as .mjs. WebSocket samples list their own dependencies.

Create an inference key on the site and set API_KEY in the environment; replace YOUR_API_KEY in cURL. Prepare local input.png/input.wav files for upload examples.

Start with a minimal request, then read the result using the response fields below. For async APIs, a returned task ID requires polling; acceptance does not mean generation has finished.

## Code examples

### curl

```bash
curl --request POST 'https://api.tu-zi.com/flux/v1/flux-3-image' \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
  "prompt": "A white ceramic cup"
}'
```

### python

```python
import json
import os
import requests

url = "https://api.tu-zi.com/flux/v1/flux-3-image"
headers = json.loads("{\"Authorization\":\"Bearer YOUR_API_KEY\",\"Content-Type\":\"application/json\"}")
headers["Authorization"] = "Bearer " + os.environ["API_KEY"]
payload = json.loads("{\"prompt\":\"A white ceramic cup\"}")
response = requests.request("POST", url, headers=headers, json=payload, timeout=120)
response.raise_for_status()
result = response.json()
if isinstance(result, dict) and (result.get("success") is False or result.get("error")):
    raise RuntimeError(json.dumps(result, ensure_ascii=False))
print(result)  # Also inspect protocol-specific status/code fields.
```

### javascript

```javascript
// Node.js 20+
const url = "https://api.tu-zi.com/flux/v1/flux-3-image";
const headers = {
  "Authorization": "Bearer YOUR_API_KEY",
  "Content-Type": "application/json"
};
headers.Authorization = 'Bearer ' + process.env.API_KEY;
const response = await fetch(url, { method: "POST", headers, body: JSON.stringify({
  "prompt": "A white ceramic cup"
}) });
if (!response.ok) throw new Error(await response.text());
const result = await response.json();
if (result?.success === false || result?.error) throw new Error(JSON.stringify(result));
console.log(result); // Also inspect protocol-specific status/code fields.
```

## Response fields

| Field | Type | Description / constraints |
| --- | --- | --- |
| id | string | Public gateway task ID. |
| polling_url | string | If supplied, verify against the gateway polling endpoint. |

Illustrative response; some endpoints show essential fields only. Optional fields may be absent.

```json
{
  "id": "task_example"
}
```

## Asynchronous workflow

Save the returned id. GET /flux/v1/get_result?id={task_id} returns Pending, Ready or Error. Read result.sample when Ready and error when Error. This gateway result route serves flux-3-image asynchronous tasks; verify effective endpoints for other models.

## Errors and retries

Check HTTP status and protocol-specific errors; do not mix error formats across protocols. For 401/403 check credentials and permissions, for 429 back off, and for 5xx check gateway/upstream status. Error bodies may contain error/message/code depending on the protocol.

Use bounded exponential backoff for reads. Do not blindly retry task creation, generation, or key mutations, to avoid duplicate billing or execution.

## Constraints

Accepts prompt, width, height, seed, prompt_upsampling, safety_tolerance and output_format. Optional model must be flux-3-image. Omitted dimensions default to 1024 in this gateway; each must be a multiple of 32 from 256 to 1440. Unknown fields are rejected. Use Bearer or x-key; do not supply conflicting credentials. This asynchronous endpoint must deliver an image URL. If the upstream returns only Base64, the site must enable Base64-to-URL conversion and have working image storage. Disabled conversion or a storage failure can produce an Error task even when submission returned HTTP 200.

## Documentation source

Definition version: 1

Reviewed: 2026-11-02

Source: https://api.tu-zi.com/en/docs/api/reference-relay-bfl-image

Related protocol guide: https://api.tu-zi.com/docs/api/images

This export contains documentation and examples only, without real credentials, account data or user requests.