Flux 2 Dev Free: High-Precision Image-to-Image Generation
Transform existing images with high fidelity using the 32B parameter Flux 2 Dev model. Upload up to 3 reference images for precise editing, restyling, and detail refinement.
Table of contents
1. Get started
Use RunComfy's API to run blackforestlabs/flux-2/dev/edit. For accepted inputs and outputs, see the model's schema.
curl --request POST \
--url https://model-api.runcomfy.net/v1/models/blackforestlabs/flux-2/dev/edit \
--header "Content-Type: application/json" \
--header "Authorization: Bearer <token>" \
--data '{
"prompt": "Change his clothes to casual suit and tie",
"image_urls": [
"https://playgrounds-storage-public.runcomfy.net/tools/7224/media-files/input-1-1.png"
]
}'2. Authentication
Set the YOUR_API_TOKEN environment variable with your API key (manage keys in your Profile) and include it on every request as a Bearer token via the Authorization header: Authorization: Bearer $YOUR_API_TOKEN.
3. API reference
Submit a request
Submit an asynchronous generation job and immediately receive a request_id plus URLs to check status, fetch results, and cancel.
curl --request POST \
--url https://model-api.runcomfy.net/v1/models/blackforestlabs/flux-2/dev/edit \
--header "Content-Type: application/json" \
--header "Authorization: Bearer <token>" \
--data '{
"prompt": "Change his clothes to casual suit and tie",
"image_urls": [
"https://playgrounds-storage-public.runcomfy.net/tools/7224/media-files/input-1-1.png"
]
}'Monitor request status
Fetch the current state for a request_id ("in_queue", "in_progress", "completed", or "cancelled").
curl --request GET \
--url https://model-api.runcomfy.net/v1/requests/{request_id}/status \
--header "Authorization: Bearer <token>"Retrieve request results
Retrieve the final outputs and metadata for the given request_id; if the job is not complete, the response returns the current state so you can continue polling.
curl --request GET \
--url https://model-api.runcomfy.net/v1/requests/{request_id}/result \
--header "Authorization: Bearer <token>"Cancel a request
Cancel a queued job by request_id, in-progress jobs cannot be cancelled.
curl --request POST \
--url https://model-api.runcomfy.net/v1/requests/{request_id}/cancel \
--header "Authorization: Bearer <token>"4. File inputs
Hosted file (URL)
Provide a publicly reachable HTTPS URL. Ensure the host allows server‑side fetches (no login/cookies required) and isn't rate‑limited or blocking bots. Recommended limits: images ≤ 50 MB (~4K), videos ≤ 100 MB (~2–5 min @ 720p). Prefer stable or pre‑signed URLs for private assets.
5. Schema
Input schema
{
"type": "object",
"title": "Input",
"required": [
"prompt",
"image_urls"
],
"properties": {
"prompt": {
"title": "Prompt",
"description": "",
"type": "string",
"default": "Change his clothes to casual suit and tie"
},
"guidance_scale": {
"title": "Guidance Scale",
"description": "Guidance Scale is a measure of how close you want the model to stick to your prompt when generating the image.",
"type": "float",
"minimum": 0,
"maximum": 20,
"default": 2.5
},
"seed": {
"title": "Seed",
"description": "",
"type": "integer",
"default": 0
},
"num_inference_steps": {
"title": "Number of Inference Steps",
"description": "The number of inference steps to perform during image generation.",
"type": "integer",
"minimum": 4,
"maximum": 50,
"default": 28
},
"image_size": {
"title": "Image Size",
"description": "Specifies the size of the image to generate. Choose a preset aspect ratio or use Custom to specify width and height between 512 and 2048 pixels.",
"type": "string",
"enum": [
"square_hd",
"square",
"portrait_4_3",
"portrait_16_9",
"landscape_4_3",
"landscape_16_9"
],
"default": "square_hd"
},
"num_images": {
"title": "Number of Images",
"description": "The number of images to generate.",
"type": "integer",
"minimum": 1,
"maximum": 4,
"default": 1
},
"enable_prompt_expansion": {
"title": "Magic Prompt",
"description": "If set to true, the prompt will be expanded for better results.",
"type": "boolean",
"default": false
},
"output_format": {
"title": "Output Format",
"description": "Specifies the output image format.",
"type": "string",
"enum": [
"jpeg",
"png",
"webp"
],
"default": "png"
},
"image_urls": {
"title": "Images",
"description": "The URLs of the images for editing. Maximum of 3 image URLs; if more are provided, only the first 3 will be used.",
"type": "array",
"items": {
"type": "string",
"format": "image_uri"
},
"maxItems": 3,
"minItems": 1,
"default": [
"https://playgrounds-storage-public.runcomfy.net/tools/7224/media-files/input-1-1.png"
]
}
}
}Output schema
{
"output": {
"type": "object",
"properties": {
"image": {
"type": "string",
"format": "uri",
"description": "single image URL"
},
"video": {
"type": "string",
"format": "uri",
"description": "single video URL"
},
"images": {
"type": "array",
"description": "multiple image URLs",
"items": { "type": "string", "format": "uri" }
},
"videos": {
"type": "array",
"description": "multiple video URLs",
"items": { "type": "string", "format": "uri" }
}
}
}
}RunComfy is the premier ComfyUI platform, offering ComfyUI online environment and services, along with ComfyUI workflows featuring stunning visuals. RunComfy also provides AI Models, enabling artists to harness the latest AI tools to create incredible art.