Pick one or more images and get a draft description for each - a starting point for the alt text on your site. Everything runs on your device; the images are never uploaded.
Example - what a result looks like (no download needed to view this):
Caption the on-device model produced for this exact image: a woman in a blue shirt and a blue and white flag
As a copyable attribute: alt="a woman in a blue shirt and a blue and white flag"
The caption above was produced ahead of time by the same model this page runs, so you can see the output shape before loading anything. It is a literal machine guess - the photo shows astronaut Sally Ride (NASA, public domain), which the model cannot know; that is exactly why every caption here needs your review.
Alt Text Generator - Describe Images On-Device
This page turns images into draft alt text without sending them anywhere. Pick up to 20 images, and each one gets a short machine-written description plus a ready-to-paste alt="..." attribute. The describing happens in your own browser: either through Chrome's built-in on-device AI when your browser has it, or through a caption model you load once with a single click. Nothing you select ever leaves your device.
The honest part first: a machine caption is a literal guess, not finished alt text. The model behind this page describes what pixels look like ("a woman in a blue shirt"), and it can get people, colors and context wrong. That is why every caption lands in an editable box - read it, correct it, cut it down to the one fact a reader needs, then copy the attribute. If an image is purely decorative, the right answer is an empty alt attribute, and the per-image hints on this page say so.
You do not need any download to get value here. With no model loaded, the same batch view becomes a writing workbench: each image shows its thumbnail, dimensions and a short guidance line matched to what the file looks like (chart, logo, screenshot or banner), with the same editable field and copyable output. Load the on-device model only when you want machine drafts for a large batch - the size (about 250 MB, one time, cached by your browser) is stated on the button before anything starts downloading.
Batch is where this saves real time. A gallery page, a product listing or a documentation set often needs dozens of descriptions in one sitting; queue the images, let each one get a draft in a few seconds, and spend your attention on editing instead of typing every sentence from scratch. The copy-all button at the end collects every finished attribute in one paste.
Two neighbouring jobs have their own pages. If you need the words printed inside an image - a sign, a receipt, a screenshot - that is optical character recognition, and the image to text (OCR) tool does it on-device the same way. And if a photo needs faces hidden before you publish it at all, the face blur tool handles that first, also without uploading anything.
Frequently Asked Questions
Are my images uploaded anywhere?
No. The images are read and described in your own browser on every path this page offers. The only network download is the caption model itself (about 250 MB, one time, kept by your browser), or nothing at all if your Chrome already has built-in on-device AI or you use the writing workbench.
Can I publish the generated captions as-is?
No - treat them as first drafts. The captions are literal scene descriptions from a small on-device model; it can misidentify people, colors and context, and it does not know names, brands or intent. Read each caption, fix what is wrong, and shorten it to what a reader actually needs.
Why is the download so large, and do I pay it every time?
The caption model is about 250 MB at its compressed size (an 87 MB image encoder plus a 159 MB text decoder). Your browser caches it after the first load, so later visits caption with no new download. The size is shown on the button before anything starts.
Does it read the text written inside an image?
No. This page describes the scene ("two cats laying on a bed"); it does not extract printed words. To pull the text out of a photo or screenshot, use the image to text (OCR) tool instead.
Can I caption many images at once?
Yes - pick up to 20 images in one go. They are processed one after another on your device, each gets its own editable caption and a copyable alt="..." snippet, and a copy-all button collects every attribute at the end.