POST/v1/alt-text🔑 API Key

Generate WCAG-compliant alt text for an image.

Request

txt
POST /v1/alt-text
Content-Type: application/json
X-API-Key: alt_YOUR_API_KEY

{
  "image_url": "https://example.com/photo.jpg",
  "language": "en",
  "context": "Product photo for ecommerce",
  "max_length": 125,
  "style": "descriptive"
}

Parameters

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | image_url | string | Yes | — | Public HTTPS URL of the image | | language | string | No | "en" | ISO 639-1 language code | | context | string | No | — | Additional context about the image | | max_length | integer | No | 125 | Max characters for alt text | | style | string | No | "descriptive" | "descriptive" or "concise" |

Response

Success (200)

txt
{
  "alt_text": "A modern ergonomic office chair with black mesh back and adjustable armrests against a white background.",
  "credits_remaining": 37,
  "wcag_compliant": true,
  "character_count": 118,
  "processing_time_ms": 1520
}

| Field | Type | Description | |-------|------|-------------| | alt_text | string | The generated alt text | | credits_remaining | integer | Credits left this billing period | | wcag_compliant | boolean | Whether the alt text meets WCAG 2.1 AA | | character_count | integer | Length of the generated alt text | | processing_time_ms | integer | Time taken to generate |

Error (400)

txt
{
  "error": {
    "code": "invalid_image_url",
    "message": "The provided URL does not point to a valid image.",
    "docs": "https://altextapi.com/docs/api-reference/errors"
  }
}

Examples

Basic Usage

txt
curl -X POST https://api.altextapi.com/v1/alt-text \
  -H "Content-Type: application/json" \
  -H "X-API-Key: alt_YOUR_API_KEY" \
  -d '{"image_url": "https://example.com/sunset.jpg"}'

With Context and Language

txt
curl -X POST https://api.altextapi.com/v1/alt-text \
  -H "Content-Type: application/json" \
  -H "X-API-Key: alt_YOUR_API_KEY" \
  -d '{
    "image_url": "https://example.com/produkt.jpg",
    "language": "de",
    "context": "Produktfoto für Online-Shop",
    "style": "concise"
  }'

Processing time

Typical processing time is 1-2 seconds. Large images (over 5MB) may take up to 4 seconds. Timeout is 15 seconds.