Flux Dev Ultra Fast
Playground
Try it on WavespeedAI!FLUX.1 [dev] is a 12B rectified-flow transformer for high-quality text-to-image generation, optimized for ultra-fast inference. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing.
Features
FLUX Dev Ultra Fast — wavespeed-ai/flux-dev-ultra-fast
FLUX Dev Ultra Fast is a lightweight, high-speed image generation and editing model built for rapid iteration. It supports both text-to-image generation and image-guided editing (image-to-image), with optional mask-based localized edits for targeted changes. This model is ideal when you need quick creative exploration, bulk variants, or fast prompt testing while maintaining strong visual quality.
Key capabilities
- Text-to-image generation for fast concepting
- Image-to-image editing for guided variations
- Masked editing (inpainting-style) for localized changes
- Adjustable strength to control how closely results follow the input image
- Custom output size, seed control, and standard image formats
- Efficient for high-volume runs and rapid experimentation
Use cases
- Rapid creative iterations for ads, thumbnails, and social content
- Style and composition exploration with quick turnaround
- Background swaps and wardrobe edits using a mask
- Product mockups and marketing variations (colorways, materials, packaging)
- Portrait enhancement workflows where speed matters (non-destructive variations)
Pricing
| Output | Price |
|---|---|
| Per image | $0.005 |
Inputs
- prompt (required): what to generate or how to edit
- image (optional): source image for image-to-image guidance
- mask_image (optional): region mask for localized edits
Parameters
- strength: how strongly the output is allowed to deviate from the input image (only for image-to-image)
- width / height: output size (e.g., 1024×1024)
- num_inference_steps: sampling steps
- guidance_scale: prompt adherence strength
- num_images: number of images to generate per run
- seed: random seed (-1 for random; set for reproducible results)
- output_format: jpeg / png / webp, etc.
- enable_base64_output: return BASE64 instead of URL (API only)
- enable_sync_mode: wait for upload and return directly (API only)
Prompting tips
- For photoreal shots, specify lens/lighting and keep subject details explicit.
- For edits, describe the change clearly and rely on the input image to preserve identity and layout.
- If using a mask, focus the prompt on what should change inside the masked region.
Example prompts
- A young couple standing side by side at a traditional wedding ceremony, warm smiles, intricate embroidered attire, realistic lighting, shallow depth of field, ultra-detailed, natural skin texture.
- Edit: keep the same pose and background, change the clothing to a modern black suit and white dress, clean studio lighting, photorealistic.
Authentication
For authentication details, please refer to the Authentication Guide.
API Endpoints
Submit Task & Query Result
# Submit the task
curl --location --request POST "https://api.wavespeed.ai/api/v3/wavespeed-ai/flux-dev-ultra-fast" \
--header "Content-Type: application/json" \
--header "Authorization: Bearer ${WAVESPEED_API_KEY}" \
--data-raw '{
"strength": 0.8,
"size": "1024*1024",
"num_inference_steps": 28,
"seed": -1,
"guidance_scale": 3.5,
"num_images": 1,
"output_format": "jpeg",
"enable_base64_output": false,
"enable_sync_mode": false
}'
# Get the result
curl --location --request GET "https://api.wavespeed.ai/api/v3/predictions/${requestId}/result" \
--header "Authorization: Bearer ${WAVESPEED_API_KEY}"
Parameters
Task Submission Parameters
Request Parameters
| Parameter | Type | Required | Default | Range | Description |
|---|---|---|---|---|---|
| prompt | string | Yes | - | The positive prompt for the generation. | |
| image | string | No | - | The image to generate an image from. | |
| mask_image | string | No | - | The mask image tells the model where to generate new pixels (white) and where to preserve the original image (black). It acts as a stencil or guide for targeted image editing. | |
| strength | number | No | 0.8 | 0.0 ~ 1.0 | Strength indicates extent to transform the reference image. |
| size | string | No | 1024*1024 | 256 ~ 1536 per dimension | The size of the generated media in pixels (width*height). |
| num_inference_steps | integer | No | 28 | 1 ~ 50 | The number of inference steps to perform. |
| seed | integer | No | -1 | -1 ~ 2147483647 | The random seed to use for the generation. -1 means a random seed will be used. |
| guidance_scale | number | No | 3.5 | 0 ~ 20 | The guidance scale to use for the generation. |
| num_images | integer | No | 1 | 1 ~ 4 | The number of images to generate. |
| output_format | string | No | jpeg | jpeg, png, webp | The format of the output image. |
| enable_base64_output | boolean | No | false | - | If enabled, the output will be encoded into a BASE64 string instead of a URL. This property is only available through the API. |
| enable_sync_mode | boolean | No | false | - | If set to true, the function will wait for the result to be generated and uploaded before returning the response. It allows you to get the result directly in the response. This property is only available through the API. |
Response Parameters
| Parameter | Type | Description |
|---|---|---|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., “success”) |
| data.id | string | Unique identifier for the prediction, Task Id |
| data.model | string | Model ID used for the prediction |
| data.outputs | array | Array of URLs to the generated content (empty when status is not completed) |
| data.urls | object | Object containing related API endpoints |
| data.urls.get | string | URL to retrieve the prediction result |
| data.has_nsfw_contents | array | Array of boolean values indicating NSFW detection for each output |
| data.status | string | Status of the task: created, processing, completed, or failed |
| data.created_at | string | ISO timestamp of when the request was created (e.g., “2023-04-01T12:34:56.789Z”) |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |
Result Request Parameters
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| id | string | Yes | - | Task ID |
Result Response Parameters
| Parameter | Type | Description |
|---|---|---|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., “success”) |
| data | object | The prediction data object containing all details |
| data.id | string | Unique identifier for the prediction, the ID of the prediction to get |
| data.model | string | Model ID used for the prediction |
| data.outputs | string | Array of URLs to the generated content (empty when status is not completed). |
| data.urls | object | Object containing related API endpoints |
| data.urls.get | string | URL to retrieve the prediction result |
| data.status | string | Status of the task: created, processing, completed, or failed |
| data.created_at | string | ISO timestamp of when the request was created (e.g., “2023-04-01T12:34:56.789Z”) |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |