An image alt text generator that keeps your images on your device
Alt text is the short description a screen reader speaks in place of an image, and what a browser shows when the image fails to load. This image alt text generator drafts it for a whole batch: an AI model on your own device looks at each picture, and simple rules turn its caption into usable alt text — no “Image of…”, no stray full stop, the right form for the image’s purpose.
Neither engine uploads your images. Desktop Chrome 148 and later can use its built-in model (Gemini Nano) through the Prompt API, which accepts images. Elsewhere, Microsoft’s open Florence-2 model (MIT licence) runs in your browser after a one-time download of 265–345 MB (more if your graphics chip runs it). Without either, a guided form and the HTML check still work.
How to write alt text with this tool
- Drop your images into Draft from images and pick their usual purpose: informative, decorative, functional (a link or button) or complex (a chart or diagram).
- Optionally describe where the images will appear — the page topic is used to point out names the alt should mention.
- Press Draft alt text. The first time, the page asks before downloading a model. Each image gets a draft, a length meter and a ready
<img>tag. - Read every draft and fix it — the model can’t know why the image is on your page. Changing an image’s purpose changes its alt and tag.
- Copy the tags, or download a CSV, edit it in a spreadsheet and import it again. To check an existing page, paste its HTML into Check HTML.
Image Alt Text Generator features
Batch drafts on your device
Up to 100 images at a time, captioned by Florence-2 (WebGPU or WebAssembly) or your browser’s built-in AI. Stop keeps the drafts already made.
Purpose-aware rules
Decorative images get alt=""; functional ones get the action you type; complex ones get a short alt plus a long description in a <figure>.
Text in images
An optional OCR pass reads the words in a picture, so a sign or a quote can become the alt text itself.
Alt text checker for HTML
Flags missing alt, empty alt on a link’s only content, file names, “image of” openings, placeholders like “photo”, duplicates and alt that repeats nearby text.
Spreadsheet round trip
An Excel-friendly UTF-8 CSV — Indian scripts included — with file, purpose, alt, long description and tag, which you can import again after editing.
What should alt text say? The W3C decision tree in short
The W3C Web Accessibility Initiative’s images tutorial (updated 8 April 2026) and its alt decision tree sort images by purpose. WCAG 2.2 success criterion 1.1.1 Non-text Content (Level A) requires a text alternative that serves the same purpose, and decorative images should be ignored by assistive technology — in HTML, alt="".
| Purpose | What the alt says | Example |
|---|---|---|
| Informative photo or graphic | The information it adds, briefly | “Volunteers collecting plastic on Calangute beach” |
| Image of text | The same words | “Sale ends Sunday — 30% off” |
| Link or button (functional) | Where it goes or what it does | “Home page”, “Download the price list (PDF)” |
| Chart, diagram, map (complex) | A short identification; the data in a long description nearby | “Bar chart of monthly sales, Jan–Jun 2026” |
| Decorative, or repeats nearby text | Nothing: alt="" | A divider line, a background texture |
Worked examples: from caption to alt text
Captioning models describe what they see in a generic way. WebAIM’s alt text article (19 October 2021) advises against “image of” or “graphic of”, because screen readers already announce an image. The rules here make that kind of edit:
- “Image of a dog on a beach” → “Dog on a beach”.
- “The image shows a man riding a bicycle.” → “Man riding a bicycle”.
- “A woman is reading a book in a park.” → “A woman is reading a book in a park” — a full sentence keeps its article; only the final full stop goes.
- The same beach photo marked decorative →
<img src="beach.png" alt="">. Leaving the attribute out makes some screen readers read the file name. - The sample HTML under Check HTML has 10 images: 4 errors, 4 things to check, 1 note and 1 image with no issues.
How long should alt text be?
WCAG sets no character limit. The often-repeated advice to stay under about 125 characters is a commonly quoted screen-reader convention, not a rule. The meter here turns amber above 125 characters and red above 150 as a nudge: say what matters in this context and move detail into visible text next to the image.
Context decides: a red saree is “Red cotton saree with a gold border” in a shop but “Priya in her wedding saree” in a family blog. Descriptive file names help too: the SEO image filename generator renames photos, and this page reads those names as hints.
Models, accuracy and limits
- Florence-2-base-ft (Microsoft, MIT; Hugging Face
onnx-community/Florence-2-base-ft, pinned revision) runs with transformers.js 3.8.1 (Apache-2.0). It writes English only; other languages go through your browser’s built-in Translator (desktop Chrome 138+), or Chrome’s Prompt API directly for Spanish and Japanese. - Models miss context and can be confidently wrong. On charts they describe the look, not the data — write that long description yourself. The OCR often runs words together; long garbled readings are hidden. Models don’t identify people.
- The HTML check is a set of rules, not a full accessibility audit. For the rest of your markup, try the HTML validator.
Image Alt Text Generator FAQ
Is this image alt text generator free and private?
Yes. Images are read by your browser’s built-in AI or by Florence-2 on your device, which downloads once after you agree. Nothing is uploaded.
Should alt text start with “image of”?
No. Screen readers already say it is an image. If the medium matters — a painting, a screenshot — say that instead.
What is the alt text for a decorative image?
An empty alt attribute, alt="", so screen readers skip it. Don’t leave the attribute out, or some read the file name.
What alt text should a logo or icon link have?
Say where the link goes or what the button does — “Home page”, “Search” — not what the picture looks like.
How many characters should alt text be?
There is no official limit. About 125 characters is a commonly quoted guide; keep it as short as the meaning allows.
Can AI write alt text for me?
It can draft it, which saves time on big batches, but it can’t know why the image is on your page. Check every draft.