AI image descriptions in your browser

What This Tool Does

This tool turns an image into a natural-language description — as a short alt text, a longer caption, or a detailed scene description. The computation runs entirely in your browser via WebAssembly and a specialized neural network trained specifically for image-to-text tasks. Three modes are available: “Short (alt text)” produces a description under 125 characters that drops straight into the alt attribute of an <img> tag; “Long” generates a richer caption suitable for figure captions and social-media posts; “Detailed” goes deeper and describes mood and background elements.

A built-in WCAG hint layer checks every result against accessibility recommendations in real time: a character counter with a traffic-light indicator when you exceed the 125-character limit, automatic detection of redundant phrases like “Image of …”, and a one-click cleanup. This prevents the most common anti-patterns that frustrate screen-reader users on the web.

How Does It Work?

Describing images is a problem from the field of computer vision — the computer has to figure out from pixel values what’s in the image and translate that into a grammatically correct sentence. Classical algorithms fail here: they detect colors, edges, and simple shapes, but not meaning. Modern vision-language models solve this with a two-stage architecture — an encoder turns the image into a compact representation, a decoder writes text from it.

The whole process runs in your browser. On first use the model is fetched once from a public model store (~75 MB for the fast variant, ~90 MB for the more accurate one), then cached locally and works offline. Every subsequent description takes 3 to 15 seconds depending on device and mode. Internally the image is normalized to a model-compatible size, pushed through the encoder network, and the decoder generates the description token by token.

The tool exposes two variants: the fast one runs on every device, including smartphones and tablets; the sharper one is intended for modern desktops and recent smartphones and tends to produce more precise descriptions — especially for product photos and scenes with multiple objects.

When Does It Produce Good Results?

Photos with a clear main subject are the sweet spot. Portraits, animal shots, landscapes, product photos with a centered subject, interior shots — anywhere the image shows a distinct scene, the model produces usable descriptions. Stock photos, blog images, and social-media posts also benefit.

Difficult cases fall into three categories:

• Brands, logos, text inside images — the model rarely identifies specific brand names and does not perform OCR. For text-in-image use our separate Image to Text tool.
• Highly abstract or decorative images — patterns, gradients, icons. The model produces overly generic descriptions like “A colorful pattern” for these. Decorative images on the web should generally use alt="" (empty alt) anyway.
• Person identification expectations — the model describes appearance and pose, but does not output names. This is intentional: face identification is privacy-sensitive, and the tool is restricted to neutral content description.

When results disappoint, the optional context field helps: “Page context: online shop for hiking gear” focuses the model on the relevant language and topic space, and you get descriptions like “Brown leather hiking boot with a red sole” instead of “A shoe”.

Frequently Asked Questions

The most common questions about usage, quality, and privacy:

How do I generate alt text for images automatically?

Upload your image into the tool above — it’s described entirely in your browser by AI. The “Short (alt text)” mode produces a description under 125 characters that drops straight into alt="…". Free, no signup, no tracking.

What makes a good alt text under WCAG?

A good alt text describes content and function of an image in at most 125 characters, without “Image of …” prefix or file extension. The tool warns you automatically when those anti-patterns appear and offers a one-click cleanup.

Does the AI describer work offline?

Yes. On first visit, the browser downloads the AI model once (~75 MB). After that every description runs fully offline from the browser cache.

Which image formats can I upload?

Input: PNG, JPG, WebP, AVIF, and HEIC (iPhone photos). HEIC is automatically decoded before the model runs. Output is text — as a .txt file or directly to your clipboard.

How long does a description take?

After the one-time model download, generating a description typically takes 3 to 15 seconds depending on device, the selected variant, and the detail mode. A progress bar shows status during processing.

Which Image Tools Are Related?

Other tools from the kittokit ecosystem that pair well:

• Image to Text (OCR) — extract written text from images, also fully in-browser. Use this tool when you need text inside images (scans, screenshots).
• Background Remover — AI-powered cutout, often the prep step for clean product descriptions.
• Image Upscaler — enlarge small preview images before you describe them.
• EXIF Viewer — read metadata from an image (camera, GPS, date) — complementary to content description.