Image Caption Generator
Generate an AI caption for an uploaded photo — pick a descriptive, social-media, SEO/alt-text, or one-phrase style.
Input
Captioned server-side with AI — this uses credits per image.
Output
Guides
Upload a photo and get an AI-written caption back in seconds — no account needed to try it, just a photo and a style. Useful for writing alt text for a website, drafting a social media post, or just getting a quick, accurate description of what's in a picture.
How to use it
- Drop or select an image (JPEG, PNG, WebP, HEIC or HEIF).
- Pick a caption style.
- Click Generate caption and copy the result.
Caption styles
- Descriptive — one clear, natural sentence covering the main subject, action and setting. Good for a general-purpose description.
- Social media caption — a short, friendly caption suited to an Instagram or Facebook post, no hashtags added.
- Alt text (SEO) — concise, objective wording under 125 characters, written for screen readers and image SEO rather than a human reader browsing a feed.
- One short phrase — five words or fewer, for a quick label or a photo filename.
Why alt text and captions aren't the same thing
A social caption is written to be read by a person scrolling past — it can be playful, brief, and skip details a viewer can already see. Alt text is read aloud by a screen reader instead of the image, so it has to describe what's actually there, stay factual, and stay short enough not to overwhelm someone navigating by ear. Search engines also index alt text directly, which is why the SEO style here optimizes for concise, literal description rather than personality.
Accuracy
The caption is generated by an AI vision model reading the pixels in your upload — it can occasionally misread small details, text within the image, or context it can't see (who a person is, a brand it can't confirm). Treat it as a strong first draft, and give it a quick read before publishing, especially for accessibility use where accuracy matters most.
Privacy
Your image is sent to our AI provider to generate the caption — see the data-handling note above the tool. It isn't stored beyond what's needed to serve the request.
Related tools
Need the image's dominant colors too? Try the Color Palette Extractor. If the file itself needs a different format first, use the Image Converter.
Use it from code
From 16 credits per callREST API
curl -X POST https://api.iotools.cloud/v1/tool/image-caption-generator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"file": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAA…",
"style": "descriptive"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `image-caption-generator` tool (Image Caption Generator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.