cinder

Privacy

Draft of 29 September 2026. Applies to the Cinder website and the Cinder iPhone app.

Draft for legal review. This describes what the website and app do today. It has not been reviewed by a lawyer and is not yet in effect.

In short

Who we are

Cinder is run by [legal entity name and address]. For anything about this policy or your data, write to cinder@converra.ai.

The website and waiting list

When you join the waiting list we collect:

The website sets no cookies, stores nothing in your browser, and loads no tracking, analytics or advertising scripts. To stop abuse, our service uses your network (IP) address to limit how often sign-ups can be sent. It keeps those counts in memory, not in the waiting list, and clears them when the service restarts. Our hosting provider may also keep standard request logs, including IP addresses, under its own terms.

If we approve your email, it's added to the invite list and we send one invite email. Joining doesn't send an email.

The app

Your account

You sign in with your email address and a six-digit code we email you. We store your email address and your account settings. We store codes and sign-in sessions only in a scrambled (hashed) form. A code expires after 10 minutes. A session lasts up to 180 days, and signing out ends it. On your iPhone, the session is kept in the iOS Keychain.

With your account we keep:

Making pictures

Making pictures sends details about your book to the cloud. You can turn this off at any time in Settings. To make pictures, the app sends our service:

Our service sends these details to AI providers, which research the book and create the pictures. The service keeps the request in memory for up to two hours, then discards it. It does not log book text, page text or pictures.

Cinder does not record audio. When you photograph a page, the text is read on your iPhone using Apple's built-in text recognition. Only the text is sent, never the photo.

When you search for a book, your iPhone sends your search words directly to Open Library and Google Books to find it.

Pictures shared between listeners

To save time and cost, some pictures are stored in a shared collection for a book and shown to other listeners of the same book. This covers pictures of a whole book's world and characters, and pictures of a chapter when Cinder found published information about that chapter. The shared collection holds the book's details, scenes and pictures, but nothing that identifies you. Pictures made from page text you add are never shared.

Your gallery on your iPhone

Pictures are saved in the app on your iPhone and are not included in iCloud or device backups. Deleting a picture or book in the app deletes it from your iPhone and, when you're signed in, from your account.

Feedback and reports

When you rate or report a picture, the rating or report and your reason are saved on your iPhone, and ratings are also saved with your account. They're also sent to us for review, with the book title, the chapter and a small preview of the picture (at most 320 pixels). These review copies don't include your email or account. They are kept until we delete them; there is no automatic deletion yet. Ask us and we'll remove yours.

What we don't collect

The app uses no advertising identifier, no tracking, and no third-party analytics or crash-reporting tools. It doesn't ask for your location, contacts, microphone or photo library. It asks for the camera only when you choose to photograph a page.

Who else handles your data

We use these services to run Cinder. Each handles only what it needs for its job.

ServiceWhat forWhat it receives
OpenAIBook research and picturesBook details, page text and choices from a picture request
Google (Gemini)Book research and picturesBook details, page text and choices from a picture request
Amazon Web ServicesStoring picturesYour account's pictures and shared book pictures
RenderRunning our service [and database: confirm host]Everything our service stores, and request logs
ResendSending sign-in codes and invitesYour email address and the message
Open Library, Google BooksFinding booksYour search words, sent from your iPhone

AI providers may keep request data for a limited time under their own policies. [Confirm each provider's retention terms and the account settings in use.] Our service runs in the United States. [Legal review: international transfer basis.]

How long we keep it

DataKept until
Waiting-list entry and answersYou ask us to delete it. [Owner: set a limit.]
Account, pictures, choices, ratingsYou delete them or your account
A picture request in progressUp to two hours, in memory
Shared book picturesThe book is removed from the shared collection
Feedback and report review copiesWe delete them. No automatic limit yet
Cost recordsKept. They hold counts and estimates, not personal details
Pictures on your iPhoneYou delete them or the app

Deleting your data

In the app, open Settings and tap Delete account. That permanently deletes your email address, sessions, consent record, reading history, choices, ratings and pictures from our service, and removes your account's pictures from your iPhone.

Deleting your account does not remove:

To have anything else deleted, or to get a copy of your data, email cinder@converra.ai from the address you use with Cinder.

Security

Data between the app, the website and our service is encrypted in transit. Codes and sessions are stored hashed. Keys for AI providers stay on our service, never in the app. No system is perfectly secure; if we learn of a breach that affects you, we'll tell you.

Children

Cinder is not meant for children under [13 / the age set by legal review], and we don't knowingly collect their data. If you think a child has given us their details, email us and we'll delete them.

Your choices and rights

You can turn off cloud picture-making in Settings, delete pictures and books, sign out, or delete your account at any time. Depending on where you live, you may have rights to see, correct, move or delete your data, or to object to how we use it. Email us to use them. [Legal review: GDPR, UK GDPR and US state law wording, lawful bases, and complaint authority.]

Changes

If we change what we collect or how we use it, we'll update this page and change its date. For significant changes, we'll also tell you in the app before they take effect.