# Fast SDXL Text-to-Image via PaySponge x402

> Fast SDXL Text-to-Image via PaySponge x402 is a paid API for AI agents from fal.x402.paysponge.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Submits a Fast SDXL text-to-image generation job to fal.ai through the PaySponge x402 payment wrapper, returning a request ID and polling URLs.

## Facts

- Endpoint: POST https://fal.x402.paysponge.com/fal-ai/fast-sdxl?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fast-sdxl-text-to-image-via-paysponge-x402-823044d3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_PIuU6xWugsbU6RRjaFb-m

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fast-sdxl-text-to-image-via-paysponge-x402-823044d3 -d '<json body>'
```

Example prompt: Generate an image of a misty mountain range at sunrise with golden light using Fast SDXL — landscape 16:9 format, 30 inference steps, guidance scale 7.5, no people, and give me 1 image as a PNG.

## When to prefer this

Prefer this endpoint when you need fast, asynchronous SDXL image generation with support for LoRA customization and custom embeddings, paid per-call via x402 USDC micropayments. Choose Fast SDXL over FLUX variants when you want the classic SDXL architecture, LoRA/embedding support, or when cost per image matters at $0.01 USDC. Use when you need an async queue-based workflow with polling rather than synchronous response.

## Known failure modes

- Missing required 'prompt' field returns a validation error
- Invalid image_size enum value causes a 400 bad request
- Payment failure via x402 protocol returns a 402 Payment Required response
- Invalid LoRA path URL causes job failure detectable via status_url
- Exceeding fal.ai rate limits returns a 429 Too Many Requests
- Job timeout or fal.ai backend error detected when polling status_url returns error state

## How this service works

POST /fal-ai/fast-sdxl

## Output

Returns a JSON object containing a request_id string, a response_url to fetch the final generated image(s), a status_url to poll job progress, a cancel_url to abort the job, and an integer queue_position indicating where the job sits in the fal.ai processing queue.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "prompt"
 ],
 "properties": {
  "seed": {
   "type": "integer"
  },
  "loras": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "path"
    ],
    "properties": {
     "path": {
      "type": "string",
      "description": "URL or path to LoRA weights."
     },
     "force": {
      "type": "boolean",
      "description": "Force this LoRA or embedding to be used when supported by the model."
     },
     "scale": {
      "type": "number",
      "description": "Scale applied before merging the LoRA with the base model."
     }
    },
    "additionalProperties": false
   }
  },
  "format": {
   "enum": [
    "jpeg",
    "png"
   ],
   "type": "string"
  },
  "prompt": {
   "type": "string",
   "description": "Prompt used for generation."
  },
  "sync_mode": {
   "type": "boolean"
  },
  "embeddings": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "path"
    ],
    "properties": {
     "path": {
      "type": "string",
      "description": "URL or path to the embedding weights."
     },
     "tokens": {
      "type": "array",
      "items": {
       "type": "string"
      },
      "description": "Optional list of trigger tokens."
     }
    },
    "additionalProperties": false
   }
  },
  "image_size": {
   "oneOf": [
    {
     "enum": [
      "square_hd",
      "square",
      "portrait_4_3",
      "portrait_16_9",
      "landscape_4_3",
      "landscape_16_9"
     ],
     "type": "string"
    },
    {
     "type": "object",
     "properties": {
      "width": {
       "type": "integer",
       "description": "Width in pixels."
      },
      "height": {
       "type": "integer",
       "description": "Height in pixels."
      }
     },
     "additionalProperties": false
    }
   ]
  },
  "num_images": {
   "type": "integer"
  },
  "request_id": {
   "type": "string",
   "description": "Optional caller-supplied identifier echoed by fal."
  },
  "expand_prompt": {
   "type": "boolean"
  },
  "guidance_scale": {
   "type": "number",
   "description": "CFG scale. Default 7.5."
  },
  "negative_prompt": {
   "type": "string"
  },
  "num_inference_steps": {
   "type": "integer"
  },
  "enable_safety_checker": {
   "type": "boolean"
  },
  "safety_checker_version": {
   "enum": [
    "v1",
    "v2"
   ],
   "type": "string"
  }
 },
 "additionalProperties": false
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "request_id",
  "response_url",
  "status_url",
  "cancel_url",
  "queue_position"
 ],
 "properties": {
  "cancel_url": {
   "type": "string",
   "format": "uri"
  },
  "request_id": {
   "type": "string"
  },
  "status_url": {
   "type": "string",
   "format": "uri"
  },
  "response_url": {
   "type": "string",
   "format": "uri"
  },
  "queue_position": {
   "type": "integer"
  }
 },
 "additionalProperties": false
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fast-sdxl-text-to-image-via-paysponge-x402-823044d3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fal.x402.paysponge.com](https://www.zero.xyz/host/fal.x402.paysponge.com/llms.txt)