Developer API.
Generate ALT text via API.
Automatically generate SEO-friendly, accessible ALT text for product images – directly from your store, CMS, marketplace or your own app.
app.autoalt.ai/api
Bearer Token
multipart/form-data
1 image = 1 credit
Introduction
The AutoAlt.ai Developer API lets you automatically generate SEO-friendly ALT text for product images using AI. Integrate the API into your e-commerce platform, CMS, marketplace, mobile app or custom workflow – and improve image accessibility and search engine optimization at scale.
Authentication
Every request is authorized via your personal API key. Pass the key in the Authorization header as a Bearer token. You can find your API key in your AutoAlt.ai account.
| Header | Value |
|---|---|
| Authorization | Bearer YOUR_API_KEY |
| Accept | application/json |
Treat your API key like a password. Never expose it in frontend/client code – make API calls server-side.
https://app.autoalt.ai/api/autoalt-generate-alt
Generate ALT Text
Generates AI-powered ALT text for an image. The endpoint supports image URLs, Base64 images, SEO keywords, custom prompts, writing styles and multilingual ALT text generation.
Content-Type: multipart/form-data
Example request (cURL)
curl --location 'https://app.autoalt.ai/api/autoalt-generate-alt' \
--header 'Authorization: Bearer YOUR_API_KEY' \
--header 'Accept: application/json' \
--form 'image_url="https://example.com/product-image.jpg"' \
--form 'language="English"' \
--form 'seo_keywords="ceramic wall tiles, glossy tiles"' \
--form 'ai_writing_style="SEO-Optimized"' \
--form 'website_domain="store.myshopify.com"'Request parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| image_url | string | Yes | Public image URL |
| base64_img | string | No | Base64-encoded image. Required when the image is not publicly accessible or is protected with an .htaccess password |
| language | string | No | ALT text language |
| ai_writing_style | string | No | AI writing style (see Writing Styles) |
| seo_keywords | string | No | SEO keywords to take into account |
| negative_keywords | string | No | Keywords to avoid |
| customPromptFromUser | string | No | Custom AI instruction / your own prompt |
| hardcoded_string_begin | string | No | Fixed text added at the beginning of the ALT text |
| hardcoded_string_end | string | No | Fixed text added at the end of the ALT text |
| autoaltai_image_name | string | No | Use image name in ALT text – on / off |
| website_domain | string | No | Website domain |
E-Commerce Fields
These optional parameters give the AI additional product information and produce more accurate, SEO-friendly and product-focused ALT text – especially useful for fashion, furniture, electronics and tiles.
| Parameter | Description |
|---|---|
| product_name | Product title / product name used to generate more accurate ALT text |
| product_brands | Brand or manufacturer name associated with the product |
| product_color | Main product color – improves visual & SEO accuracy |
Why use these parameters?
Using product-related data helps the AI generate:
Example with product data
curl --location 'https://app.autoalt.ai/api/autoalt-generate-alt' \
--header 'Authorization: Bearer YOUR_API_KEY' \
--form 'image_url="https://example.com/product-image.jpg"' \
--form 'product_name="Premium Ceramic Wall Tile"' \
--form 'product_brands="AutoTiles"' \
--form 'product_color="White"'“White premium ceramic wall tile by AutoTiles for modern bathroom interiors”
Writing Styles
The ai_writing_style parameter controls the tone, structure and writing style of the generated ALT text – matching your brand voice, SEO strategy or accessibility requirements.
Supported Writing Styles
| Writing Style | Description |
|---|---|
| SEO-Optimized | Keyword-rich for SEO improvement |
| Neutral | Clear, balanced, and objective |
| Friendly | Warm, approachable, and informal |
| Professional | Polished and business-appropriate |
| Casual | Relaxed and conversational |
| Witty | Clever and playful tone |
| Confident | Bold and assertive writing |
| Empathetic | Sensitive and understanding tone |
| Inspiring | Motivational and uplifting |
| Technical | Precise and jargon-friendly |
| Minimalist | Simple and concise |
| Luxury | Elegant and premium wording |
| Youthful | Trendy and modern style |
| Quirky | Fun and creative language |
| Sales-Oriented | Persuasive and conversion-focused |
| Informative | Educational and factual |
| Formal | Structured and traditional |
| Authoritative | Expert and trustworthy tone |
Example request (Writing Style)
curl --location 'https://app.autoalt.ai/api/autoalt-generate-alt' \
--header 'Authorization: Bearer YOUR_API_KEY' \
--form 'image_url="https://example.com/product.jpg"' \
--form 'ai_writing_style="SEO-Optimized"'Output comparison (same image)
Modern white ceramic wall tiles with glossy finish for bathroom and kitchen interiors
White glossy ceramic wall tiles
Premium glossy white ceramic wall tiles designed for elegant modern interiors
https://app.autoalt.ai/api/autoalt-verify-api-key
Verify API Key
Validates whether an AutoAlt.ai API key is active and valid – before you make actual API requests.
This endpoint is useful for:
Request parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| apiKey | string | Yes | Dein AutoAlt.ai API-Key |
Request (cURL)
curl --location --request POST \
'https://app.autoalt.ai/api/autoalt-verify-api-key' \
--header 'Authorization: Bearer YOUR_API_KEY' \
--form 'apiKey="YOUR_API_KEY"'Response
{
"is_verify": true
}{
"is_verify": false
}is_verify returns true if the API key is valid, otherwise false.
Response & Credits
On success the API returns a JSON object with the generated ALT text, the language and the number of credits used. 1 image = 1 credit – regardless of format or number of output languages.
{
"alt_text": "White glossy ceramic wall tiles for modern bathroom interior",
"total_credit": 50,
"credits": 36,
"used_credits": 14,
"asset_id": "deb9a028f5c7c64c0631393432393546e39c62cbafc92ce8",
"filename": null,
"imagename": null,
"used_plan": "free",
}Best Practices
Especially recommended for fashion, furniture, electronics and tile products.