Use RunComfy's API to run blackforestlabs/flux-2-klein/4b/text-to-image. For accepted inputs and outputs, see the model's schema.
curl --request POST \
--url https://model-api.runcomfy.net/v1/models/blackforestlabs/flux-2-klein/4b/text-to-image \
--header "Content-Type: application/json" \
--header "Authorization: Bearer <token>" \
--data '{
"prompt": "A majestic snow leopard perched on a frost-covered rocky ledge in the Himalayas at dawn, thick silver-grey fur with inky rosettes, piercing glacier-blue eyes, warm golden first light grazing the peaks behind, drifting snow particles, ultra-detailed wildlife photography, 85mm telephoto, shallow depth of field"
}'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.
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-klein/4b/text-to-image \
--header "Content-Type: application/json" \
--header "Authorization: Bearer <token>" \
--data '{
"prompt": "A majestic snow leopard perched on a frost-covered rocky ledge in the Himalayas at dawn, thick silver-grey fur with inky rosettes, piercing glacier-blue eyes, warm golden first light grazing the peaks behind, drifting snow particles, ultra-detailed wildlife photography, 85mm telephoto, shallow depth of field"
}'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 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 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>"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.
{
"type": "object",
"title": "Input schema",
"required": [
"prompt"
],
"properties": {
"prompt": {
"title": "Prompt",
"description": "",
"type": "string",
"default": "A majestic snow leopard perched on a frost-covered rocky ledge in the Himalayas at dawn, thick silver-grey fur with inky rosettes, piercing glacier-blue eyes, warm golden first light grazing the peaks behind, drifting snow particles, ultra-detailed wildlife photography, 85mm telephoto, shallow depth of field"
},
"width": {
"title": "Resolution - Width (px)",
"description": "",
"type": "integer",
"minimum": 64,
"maximum": 2048,
"default": 1024
},
"height": {
"title": "Resolution - Height (px)",
"description": "",
"type": "integer",
"minimum": 64,
"maximum": 2048,
"default": 1024
}
}
}{
"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.