Privacy

Last updated: October 17, 2026

Alter is a photo library for the Mac, made by Twilightscapes, the team behind ALTtext.org. The short version: your photos and your library stay on your Mac. Alter has no account, no analytics, no crash reporting, no ads and no tracking. It only goes online for the things listed below, and only when you use them.

On your Mac

Your library, your photos, your edits, keywords, ratings, albums and locations are stored in your library on your Mac (or wherever you keep it). We never receive them.

• Faces. Face recognition runs entirely on your Mac. Alter turns each face into a set of numbers to find the same person in other photos. The numbers, and the names you give people, stay in your library and are never sent anywhere.
• Select. The Select tool's object finding runs on your Mac too. No photo leaves it.
• Sign-ins. If you connect Bluesky, the sign-in is kept in your Mac's Keychain.

When Alter goes online

ALT text

When you ask Alter to write ALT text, it sends a smaller copy of that photo to alttext.org. For a video, it sends up to eight still frames, plus a transcript of the speech in it made on your Mac. alttext.org passes them to Google's Gemini API and returns the description. We don't store the photo, the frames, the transcript or the description. Our Gemini account is a paid one, so Google doesn't use what we send to train its models.

To keep the service fair, alttext.org keeps a count of how many descriptions are written each day. It's kept against your network address, or against your ALTtext key if you have Pro. The counts contain no photos and no text.

Buying Alter Pro

From the Mac App Store: Apple handles the payment, and we never see your name, Apple Account or payment details. Unlimited ALT text comes with Pro, so once after you buy, Alter sends Apple's signed record of that purchase to alttext.org, which checks it with Apple and issues an ALTtext key. We keep that purchase's transaction number together with the key, so the same purchase always gets the same key back.

From altermedia.app: payment is handled by Stripe, as described in the ALTtext privacy policy. We keep the key we issue, the email address you gave and Stripe's customer reference.

Maps and place names

Maps, and the place names shown for your photos, come from Apple's map services. To name a place, Alter sends only its location, rounded to about a kilometre, and never a photo. This is covered by Apple's privacy policy. You can turn place names off in Settings (Look up place names).

Downloads

The first time you use Faces or Select, Alter downloads the model it needs from Hugging Face. Alter Pro's font picker downloads fonts from Google Fonts. These are plain downloads. Nothing of yours is sent.

Places you post to

If you connect Bluesky, post a video, or publish a web gallery to GitHub, Alter sends what you chose to post to that service, under your own account. The sign-in happens on that service's own page. Subscribing a gallery on your Apple TV saves its address in your own iCloud, for the Twilightscapes app.

Feedback

If you send feedback from altermedia.app, we keep what you wrote, the Alter version if you gave it, and your email address if you left one so we can reply.

Who else is involved

• Google writes ALT text descriptions (Gemini API).
• Apple handles App Store purchases and map services.
• Netlify hosts altermedia.app and alttext.org, and stores the usage counts, keys and feedback.
• Stripe handles purchases made on altermedia.app.

We don't sell your data, and we don't use advertising or tracking of any kind.

Your choices

Alter works fully offline apart from the features above. To ask about, or delete, the key and purchase record that go with your Alter Pro, email support@alttext.org.

Children

Alter isn't directed to children under 13, and we don't knowingly collect their data.

Changes

When this page changes, the date at the top changes too, and anything important will be noted on the site.

Contact

Questions? support@alttext.org.