# Image Alt Text Generator

> Image Alt Text Generator is a paid API for AI agents from agentsvc.io, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-11).

Generates descriptive, accessible alt text for images from a URL or base64 input, with optional context and language control.

## Facts

- Endpoint: POST https://agentsvc.io/api/v1/proxy/image-alt-text?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/image-alt-text-generator-e47b5526
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_euRhXKKMW5_ztJ3XdEh-e

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 image-alt-text-generator-e47b5526 -d '<json body>'
```

Example prompt: Can you generate alt text for this image — https://example.com/mountain-photo.jpg — it's being used as the hero image on a travel website homepage, and I need the output in English.

## When to prefer this

Choose this endpoint when you need production-quality, AI-generated alt text for accessibility compliance (WCAG), SEO enrichment, or CMS automation — especially when you want both a concise alt attribute and a detailed long description in one call. It is ideal for agents that process images at scale, need multilingual output, or require HTML-ready snippets without building their own vision pipeline. Prefer this over generic vision APIs when you specifically need accessibility-oriented descriptions with decorative-image detection.

## Known failure modes

- Image URL not publicly accessible or returns 4xx/5xx — endpoint cannot fetch the image
- Image exceeds 15 MB size limit — request rejected
- Invalid base64 encoding if using image_base64 input
- Unsupported image format — only common formats like JPEG, PNG, GIF, WebP accepted
- Context string exceeds 500 character limit
- Network timeout fetching the remote image URL

## How this service works

86 APIs for AI agents: web scraping and crawling to Markdown, AI summaries, data extraction and cited answers, screenshots and PDF, PDF, OCR and document conversion, news, paper and developer search and more, paid per call with USDC on Base, Solana, Polygon or Arbitrum via x402. No account, no API key, free sample on every service.

## Output

Returns a JSON object with: the generated alt text string, an HTML-ready alt attribute snippet, image dimensions (width, height), the AI model used, the language of the output, a boolean indicating whether the image is decorative (and thus should have empty alt), any text detected within the image, and a long-form detailed description of the image for extended accessibility use cases.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "context": {
   "type": "string",
   "description": "Where the image is used, max 500 chars"
  },
  "language": {
   "type": "string",
   "description": "Language of the alt text, default English"
  },
  "image_url": {
   "type": "string",
   "description": "Public image URL (max 15 MB)"
  },
  "image_base64": {
   "type": "string",
   "description": "Base64 image instead of a URL"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "html": "alt=\"Panoramic view of forested mountain ridges with rocky cliffs under cumulus clouds, with a lake visible at the lower right\"",
   "image": {
    "width": 800,
    "height": 359,
    "original": {
     "width": 1280,
     "format": "jpeg",
     "height": 575,
     "size_bytes": 221419
    }
   },
   "model": "claude-haiku-5-5",
   "alt_text": "Panoramic view of forested mountain ridges with rocky cliffs under cumulus clouds, with a lake visible at the lower right",
   "language": null,
   "decorative": false,
   "text_in_image": null,
   "long_description": "A wide landscape photo of a steep, forested mountain with a flat rocky summit and exposed limestone cliffs at its top. Lower slopes show green meadows and scattered farm buildings, while snow-capped peaks rise in the distance on the right. A blue lake appears at the far lower right beneath a blue sky with white clouds."
  },
  "success": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/image-alt-text-generator-e47b5526/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentsvc.io](https://www.zero.xyz/host/agentsvc.io/llms.txt)