AI Image Caption Generator
Generate natural language descriptions for any image using AI. Perfect for alt-text and accessibility — runs entirely in your browser.
Processed on your device — never uploaded
Upload an Image
Your image never leaves your deviceWorks offline after first use
This tool works best on desktop (large AI engine: ~250MB)
Frequently Asked Questions
How does AI image captioning work?
This tool uses the ViT-GPT2 model, which combines a Vision Transformer (ViT) image encoder with a GPT-2 text decoder. The ViT analyzes the visual content of your image, and GPT-2 generates a natural language description. Everything runs locally in your browser using WebAssembly.
Can I use the generated captions as alt text?
Yes! The captions are designed to describe the visual content of images, making them excellent starting points for alt text. You can use the "Use as alt text" button to get ready-to-paste HTML code. For best accessibility, review and refine the caption to ensure it accurately conveys the image's purpose in your specific context.
Why is alt text important for accessibility?
Alt text (alternative text) provides a text description of images for people who use screen readers, have slow internet connections, or have images disabled. It's essential for web accessibility (WCAG compliance), improves SEO, and ensures your content is available to all users regardless of their abilities or circumstances.
Is my image uploaded to a server?
No. All processing happens entirely on your device, in your browser. Your images never leave your device. The AI model is downloaded once (~250 MB) and cached for future use, so it works offline after the first use.