Privacy
In short
- To make pictures, Cinder sends details about the book you choose to AI services. It never sends audio or page photos.
- Your pictures are kept on your iPhone. When you're signed in, a copy is also kept with your account.
- We may use the pictures Cinder makes, and the book details they came from, to improve Cinder, including to train AI models. That never includes your email, your account details, or text you add.
- We don't sell your data or show ads. Usage analytics are optional and off until you allow them.
- You can delete your account in the app. A few things are kept after that, and they're listed below.
Who we are
Cinder is run by Converra, Inc., a Delaware corporation in the United States, which decides how your data is used. Cinder is currently offered in the United States. For anything about this policy or your data, write to privacy@cindergo.com.
The website and waiting list
When you join the waiting list we collect:
- Your email address, so we can send your invite.
- Two optional answers, if you give them: where you listen to audiobooks, and a book you'd like to see. They help us decide what to work on first.
The website uses optional usage analytics, described below. It also keeps your choice on book pages: if you turn “Show spoilers” off, that setting stays in browser storage and is never sent to us. To stop abuse, our service uses your IP address to limit sign-ups, keeping counts in memory until it restarts. Our hosting providers may keep standard request logs, including IP addresses.
Optional usage analytics
If you choose “Allow analytics” on the website or turn on “Share usage analytics” in the app’s Settings, we send basic usage events to PostHog in a dedicated Cinder project, separate from Converra’s analytics. These include website page groups and waiting-list steps, and app screen visits and picture-making steps. Analytics are off until you allow them. They do not include your email, account ID, form answers, book details, page text, pictures or session recordings. We do not use analytics for advertising.
The website keeps your analytics choice in browser storage but uses no analytics cookies or persistent visitor identifier; its anonymous identifier lasts for the current page. We omit URL queries, fragments, book-page names and referring addresses. Browsers sending Do Not Track or Global Privacy Control do not send analytics. Use “Analytics choices” in the footer to change your choice.
The app keeps your choice and a randomly generated analytics identifier on your iPhone. This identifier is separate from your Cinder account and is reset when you sign out, your session ends, you delete your account, or you turn off analytics. Events include basic app and device information. Turning analytics off stops future collection; it does not delete events already received. PostHog receives your network address when a request reaches it. The Cinder project uses PostHog’s free plan, which retains analytics for up to one year. We may delete them sooner. For deletion requests, contact us below.
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:
- whether you allowed picture-making in the cloud, and when
- the books you've made pictures for, and the last chapter
- the styles and character looks you chose
- short captions of scenes already shown, so you don't get the same one twice
- your pictures and their details
- your thumbs-up and thumbs-down ratings, and your reasons
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:
- the book's title and author, the chapter or page, and a short description of the book
- any page text you add, up to 2,000 characters
- the styles and character looks you chose, and captions of earlier pictures
- the reasons you gave for recent thumbs-down ratings, so later pictures avoid the same problems
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.
Public book pages
Shared chapter pictures are also published on public pages at cindergo.com/books, one page for each book and each chapter. Anyone can see these pages, and search engines can index them. They show the book's title and author, the chapter, and each picture's caption and style, but nothing that identifies you or who made a picture. A picture that may spoil the book can be blurred on the page. Anyone can report a picture from its page, and we remove pictures that break our rules, and every picture of a book removed from the shared collection.
Improving Cinder with pictures
The pictures Cinder makes are Converra's, as the Terms explain. We may keep and use them, together with the book details, styles and captions they came from, to improve Cinder, including to train or tune AI models. We remove your email and account details before using pictures this way. We don't use text you add, such as a page you type or photograph, or your email, account details or ratings, to train AI models. Deleting a picture or your account removes it from your gallery and account, but it may already have been used to improve Cinder.
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 or advertising tracking. Optional analytics are described above; automatic crash reporting and session recording are disabled. 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, and share with each only what it needs for its job.
| Service | What for | What it receives |
|---|---|---|
| OpenAI | Book research and pictures | Book details, page text and choices from a picture request |
| Google (Gemini) | Book research and pictures | Book details, page text and choices from a picture request |
| Amazon Web Services | Storing pictures | Your account's pictures and shared book pictures |
| Render | Running our service and its database | Everything our service handles and stores, and request logs |
| Resend | Sending sign-in codes and invites | Your email address and the message |
| Open Library, Google Books | Finding books | Your search words, sent from your iPhone |
| Google Books, Gutendex, Project Gutenberg | Finding published information and public-domain text about a book | The book's title and author, sent by our service |
| PostHog | Optional usage analytics | Usage events, a random analytics identifier, basic app/device information and network requests |
| Cloudflare | Delivering the website | Your IP address and the pages you request |
| Google Workspace | Our email | Messages you send us |
These providers may keep request data for a limited time under their own terms, for example to detect abuse. We use their business services, whose terms don't allow them to use your data to train their models. Our service and these providers are in the United States, so if you use Cinder from elsewhere, your data is transferred there. Where the law requires a safeguard for that transfer, we rely on the providers' data protection terms, such as the European Commission's standard contractual clauses.
How long we keep it
| Data | Kept until |
|---|---|
| Waiting-list entry and answers | 12 months after you join, or sooner if you ask. An invite, once sent, stays with your account |
| Account, pictures, choices, ratings | You delete them or your account |
| A picture request in progress | Up to two hours, in memory |
| Shared book pictures | The book is removed from the shared collection |
| Feedback and report review copies | We delete them. No automatic limit yet |
| Optional analytics | Up to one year under the current PostHog plan, or sooner if we delete them |
| Cost records | Kept. They hold counts and estimates, not personal details |
| Pictures on your iPhone | You 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:
- shared book pictures that other listeners use
- feedback review copies (ask us and we'll delete them)
- your waiting-list entry and invite (ask us and we'll delete them)
- pictures you made before you signed in, which stay on your iPhone until you delete them or the app
- copies an AI provider or our hosting provider keeps under its own policy
To have anything else deleted, or to get a copy of your data, email privacy@cindergo.com 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 a breach affects your data, we'll notify you as the law requires.
Children
Cinder is not meant for children under 13, 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. You can ask us for a copy of your data, or to correct or delete it, by emailing privacy@cindergo.com from the address you use with Cinder. We'll reply within 30 days. Depending on where you live, you may have more rights, such as to object to how we use your data, and we'll honor the rights your local law gives you.
If you're in the European Economic Area or the United Kingdom, we use your data on these legal bases: your consent for the waiting list, your optional answers and cloud picture-making, which you can withdraw at any time; to provide the service you asked for, for your account and pictures; and our legitimate interest in keeping Cinder safe and working, for limiting sign-ups and reviewing reports. You can also complain to the data protection authority where you live.
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 or by email before they take effect.