# Alt Text & Captions — Generate alt text for images on Mac

Write accessible descriptions for images, for websites, documents and social posts. Part of OneMacTools, 151 private tools in one native Mac app (macOS 26 or later); category: On-device AI. Runs on your Mac; nothing is uploaded.

Vision identifies what's in each image, who's in it and any text, and Apple Intelligence writes concise alt text or a social caption. Descriptions are saved to a CSV and can be embedded into copies of the images.

Page: https://www.onemactools.com/tools/alt-text-generator · Download: https://www.onemactools.com/download · Pricing: https://www.onemactools.com/pricing

## How to use it
1. **Drop your images.** Add one image or a whole batch: photos, screenshots, graphics or slides.
2. **Choose what to write.** In the right-hand panel, set Write to Alt text for websites and documents, or Social caption for posts.
3. **Decide on embedded copies.** Leave Save copies with the description embedded on if you want the description stored inside copies of the images.
4. **Click Describe.** Vision recognises the main subjects, counts the people and reads any text in each image. Apple Intelligence turns that into a short description.
5. **Use the descriptions.** They're saved in Alt text.csv (or Captions.csv) in a new dated folder in Downloads › OneMacTools. If you described a single image, its description is also shown in the window and copied to the clipboard.

## Options
- **Write:** Alt text, the default, writes a factual description under 125 characters that doesn't start with “Image of”, ready for a website, a document or an app. Social caption writes a friendly one-sentence caption with two or three hashtags.
- **Save copies with the description embedded:** On by default. Saves a copy of each image with “described” added to its name and the description written into its caption and description fields, which Photos, Finder and many web tools read. Turn it off if you only need the CSV.

## Tips
- Read every description before you publish it. It's built from what your Mac can recognise, so add names, places and context only you know.
- Good alt text explains what matters on the page. Edit the draft to say why the image is there, not just what's in it.
- Purely decorative images, such as dividers and background patterns, usually need empty alt text rather than a description.
- Text in an image, such as a poster or a slide, is read and included. Check its spelling against the image.
- Adjust the hashtags in social captions to match your account before posting.

## Questions
**How do I generate alt text for images on a Mac?**
Drop the images onto Alt Text & Captions, leave Write on Alt text and click Describe. Each image gets a short description, saved in a CSV you can copy from.

**How long is the alt text?**
Under 125 characters, which is short enough for screen readers and for most website and content management fields.

**Can it write captions for social media posts?**
Yes. Set Write to Social caption for a friendly one-sentence caption with two or three hashtags.

**Does it recognise who is in a photo?**
No. It notes that there are people, and how many, but doesn't identify anyone. Add names yourself where they matter.

**Where is the description stored in the image?**
In the copy's IPTC caption and TIFF image description fields, and the PNG description for PNG files. Photos, Finder and many web tools read these. Your original image isn't changed.

**Is AI-written alt text good enough for accessibility?**
It's a solid first draft that saves time on large batches. Review each one and add the context a reader needs, because only you know why the image is on the page.