Flux Fill Dev

FLUX Fill Dev is a powerful AI-powered inpainting model that fills in masked regions of images based on text prompts. Upload an image and mask, describe what should appear in the masked area, and the model seamlessly generates new content that blends naturally with the surrounding image.

Why It Stands Out

Precise inpainting: Generate new content only in masked regions while preserving the rest.
Prompt-guided generation: Describe exactly what should appear in the masked area.
Prompt Enhancer: Built-in AI-powered prompt optimization for better results.
LoRA support: Apply up to 3 custom LoRA models for specific styles.
Flexible resolution: Width and height adjustable from 256 to 1536 pixels.
Batch generation: Create multiple variations in a single request.
Reproducibility: Use the seed parameter to recreate exact results.

Parameters

Parameter	Required	Description
image	Yes	Source image to edit (upload or public URL).
mask_image	Yes	Mask image (white = generate, black = preserve).
prompt	Yes	Text description of what to generate in the masked area.
width	No	Output width: 256–1536 pixels (default: 1024).
height	No	Output height: 256–1536 pixels (default: 1024).
num_inference_steps	No	Quality/speed trade-off (default: 28).
seed	No	Set for reproducibility (default: 0).
guidance_scale	No	Prompt adherence strength (default: 30).
num_images	No	Number of images to generate (default: 1).
loras	No	LoRA models to apply. Up to 3 LoRAs.

How to Use

Upload your source image — drag and drop a file or paste a public URL.
Upload or create a mask image — white areas will be regenerated, black areas preserved.
Write a prompt describing what should appear in the masked region. Use the Prompt Enhancer for AI-assisted optimization.
Add LoRAs (optional) — apply up to 3 custom style LoRAs.
Adjust parameters (optional) — set dimensions, guidance scale, and num_images.
Click Run and download your edited image.

Best Use Cases

Object Replacement — Replace objects in images with new ones.
Background Editing — Change or extend backgrounds seamlessly.
Content Addition — Add new elements like clothing, accessories, or objects.
Photo Repair — Remove unwanted elements and fill with appropriate content.
Creative Compositing — Blend new elements into existing scenes naturally.

Pricing

Output	Price
Per image	$0.035

Pro Tips for Best Quality

Create clean, precise masks — white for areas to regenerate, black for areas to keep.
Be specific in your prompt about what should appear in the masked area.
Use higher guidance scale (25–35) for stronger prompt adherence.
Generate multiple images (num_images > 1) to explore variations.
Use LoRAs to apply consistent styles across multiple inpainting jobs.
Ensure mask edges are smooth for better blending results.

Notes

Maximum of 3 LoRAs per generation.
Width and height must be between 256 and 1536 pixels.
Ensure uploaded image URLs are publicly accessible.
Processing time varies based on resolution and current queue load.
Please ensure your content complies with usage guidelines.

Flux Fill Dev API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/wavespeed-ai/flux-fill-dev with your input as JSON. The endpoint returns a prediction id; poll the prediction endpoint until status flips to completed, then read the output URL from data.outputs[0]. Examples for Flux Fill Dev below.

HTTP example

# Submit the prediction
curl -X POST "https://api.wavespeed.ai/api/v3/wavespeed-ai/flux-fill-dev" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY" \
  -d '{
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "image": "https://example.com/your-input.jpg",
    "size": "1024*1024",
    "num_inference_steps": 28,
    "seed": 0,
    "guidance_scale": 30,
    "num_images": 1
}'

# Response includes a prediction id. Poll for the result:
curl -X GET "https://api.wavespeed.ai/api/v3/predictions/{request_id}/result" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY"

# When status is "completed", read the output from data.outputs[0].

Node.js example

// npm install wavespeed
const WaveSpeed = require('wavespeed');

const client = new WaveSpeed(); // reads WAVESPEED_API_KEY from env

const result = await client.run("wavespeed-ai/flux-fill-dev", {
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "image": "https://example.com/your-input.jpg",
        "size": "1024*1024",
        "num_inference_steps": 28,
        "seed": 0,
        "guidance_scale": 30,
        "num_images": 1
});

console.log(result.outputs[0]); // → URL of the generated output

Python example

# pip install wavespeed
import wavespeed

output = wavespeed.run(
    "wavespeed-ai/flux-fill-dev",
    {
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "image": "https://example.com/your-input.jpg",
    "size": "1024*1024",
    "num_inference_steps": 28,
    "seed": 0,
    "guidance_scale": 30,
    "num_images": 1
}
)

print(output["outputs"][0])  # → URL of the generated output

Flux Fill Dev API — Frequently asked questions

What is the Flux Fill Dev API?

Flux Fill Dev is a WaveSpeedAI model for image editing, exposed as a REST API on WaveSpeedAI. FLUX.1 Fill [dev] is a 12B-parameter rectified flow transformer for text-guided image inpainting that fills areas of existing images from text prompts. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing. You can call it programmatically or try it from the playground above.

How do I call the Flux Fill Dev API?

POST your input parameters to the model's REST endpoint (shown in the API tab of this playground) with your WaveSpeedAI API key in the Authorization header. Submission returns a prediction ID; poll the prediction endpoint until status flips to "completed", then read the output URL from the result. The playground generates a ready-to-paste code sample in Python, JavaScript, or cURL for whatever inputs you've set. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/wavespeed-ai/flux-fill-dev.

How much does Flux Fill Dev cost per run?

Flux Fill Dev starts at $0.035 per run. That figure is the base price — the final charge scales with the parameters you set in the form (output size, length, count, references, or whatever knobs this model exposes), so a higher-quality or larger output costs more than a minimal one. The exact cost for your current input is shown live next to the Generate button before you submit, and the actual per-call charge is recorded on the prediction afterwards.

What inputs does Flux Fill Dev accept?

Key inputs: `prompt`, `image`, `size`, `seed`, `guidance_scale`, `num_inference_steps`. The full JSON schema (types, defaults, allowed values) is rendered above the Generate button and mirrored in the API reference at https://wavespeed.ai/docs/docs-api/wavespeed-ai/flux-fill-dev.

How long does Flux Fill Dev take to generate?

Average end-to-end generation time on WaveSpeedAI is around 23 seconds per request — measured across recent runs. Queue time scales with global demand; live status is visible in the prediction record.

Can I use Flux Fill Dev outputs commercially?

Commercial usage rights depend on the model's license, set by its provider (WaveSpeedAI). The license summary appears on the model card above; see WaveSpeedAI's Terms of Service for platform-level conditions.

ExamplesView all

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FLUX Fill Dev