Privacy Policy

Last updated: 4 November 2026

This policy explains what the Kelda app and this website collect, why, who helps us process it, and how you can delete it. Kelda (“we”, “us”) makes the Kelda reading app for iPhone and Android.

The short version

• You don't need to give us your name, email address or phone number. The app uses a guest account.
• We sync your reading (progress, saved lines, settings, stats) to that account so it's backed up and works on your other devices.
• No ads, no tracking across apps or websites, and no third-party analytics. We don't sell your data.
• Books you import stay on your phone unless you choose to sync them.
• You can delete your account and its data at any time in the app: You › About › Delete account.

What we collect and why

A guest account

The first time you open the app, it signs you in to an anonymous guest account with Firebase Authentication, a Google service. This gives you a random user ID. We use it to keep your data separate from everyone else's and to sync it between your devices.

Your reading data

The app stores this on your phone and syncs it to your account in Google Cloud Firestore:

• Your place in each book, your shelf and when you started or finished a book.
• Lines you loved: the saved text, with its book and chapter.
• Cards you loved, and your settings and moods.
• Daily reading stats (minutes, pages, words and pieces read), used for your goal, streak and Year in Reading.
• Study mode items, such as saved words, flashcards, reading plans and quiz results.
• A compact model of your reading tastes, which the app uses to choose your feed.
• A random install ID, so the app can merge data from more than one device.

We use this to run the app: to sync, to back up, and to personalise your feed.

How you use the feed

To recommend passages, the app records simple events, such as skipping, reading, loving, saving or sharing a card, or tapping Keep reading. Each event holds your user ID, the card and book, the kind of event and the day. It holds no text, no device details and no location.

Every hour, our server folds these events into recommendations that aren't about any one person, such as “readers who loved this also loved…” and what's popular in each mood. The raw events are then deleted, usually within about an hour. To build those recommendations, the server keeps a short list of the cards you engaged with most recently (up to 50, for up to 90 days).

Books you import are never used for recommendations.

Purchases

If you subscribe to Premium, Apple or Google takes the payment. We never see your card details. After a purchase, the app sends the store's purchase token or signed transaction, the product, the price and the currency to our billing service, which checks it with Apple or Google. We then record your subscription on your account: the plan, its status, when it renews or ends, whether it's a trial, and the store's transaction ID.

AI helpers (Premium, only when you tap them)

Explain this, Previously on… recaps, Ask the book, and study mode's Define and chapter quizzes use AI. Nothing is sent until you tap one of them. When you do, our server sends the relevant text from the book, plus any word, sentence or question you selected or typed, to OpenRouter. OpenRouter passes it to an AI model provider to write the answer. We don't send your user ID, your name or your reading history with it. We use OpenRouter with zero data retention: OpenRouter only routes requests to model providers that don't store your prompts or use them for training.

Explanations, recaps, definitions and quizzes are cached and reused for other readers, with no link to you. Questions you type are not stored by us. We keep a daily count of AI requests per account to apply fair-use limits.

Read aloud (Premium)

Narration for a chapter is generated from the book's text by fal.ai, using an ElevenLabs voice model, and then cached for all readers. Only the book's text is sent, nothing about you. We keep a daily count of newly generated chapters per account to apply fair-use limits. Books you import are read by your phone's own voice, on your phone.

Books you import

EPUBs you import stay on your device. They are never sent to the AI helpers or the AI voices, and never used for recommendations.

If you have Premium and turn on Sync my imported books (off by default), the EPUB files, their covers and their details are stored privately in your account in Firebase Cloud Storage and Firestore, so your other devices can download them. Only you can open them. Turning sync off deletes the cloud copies. If Premium ends, the cloud copies are deleted 30 days later. The copies on your devices stay.

App Check

To protect our servers from abuse, the app uses Firebase App Check. It asks Apple (App Attest or DeviceCheck) or Google (Play Integrity) to confirm that requests come from a genuine copy of the app. App Check doesn't tell us who you are.

Downloading books

Books and the catalog are downloaded from our content server, which runs on Cloudflare. Like any web server, it receives your IP address and basic request details, which Cloudflare processes to deliver the files, keep the service secure and keep it running.

Notifications

Kelda only uses local notifications that your phone schedules for itself. If you start a free trial and allow notifications, the app schedules a reminder 2 days before you're charged. We don't send push notifications, and no notification data leaves your phone.

Highlight export to Readwise or Notion (Premium, optional)

If you connect Readwise or Notion, the access token you paste in is kept in your phone's secure storage. When you export, your saved lines go straight from your phone to that service, and its privacy policy applies. We don't receive the token.

Sharing and copying

Sharing a quote card or copying a line uses your phone's share sheet and clipboard. We don't see what you share or where.

What we don't do

• We don't show ads, and we don't use advertising IDs.
• We don't track you across other companies' apps or websites.
• We don't use third-party analytics or crash-reporting tools.
• We don't sell or rent your personal data, or share it with data brokers.
• This website sets no cookies and runs no analytics.

Who processes data for us

We use these service providers. They only process data to provide their service to us.

• Google Firebase and Google Cloud: guest accounts, data sync (Firestore), file storage for synced imports, our server functions and App Check.
• Cloudflare: book downloads and this website.
• OpenRouter, and the AI model providers it routes requests to: the AI helpers.
• fal.ai (ElevenLabs voice models): read-aloud narration, from book text only.
• Apple and Google: payments, subscription management, and the app checks used by App Check.
• Our billing service: verifies purchases with Apple and Google.

Where your data is stored

Your data is stored with Google Cloud and processed by the providers above, who may handle it in the United States and other countries. Data is encrypted in transit and at rest. Our database rules only let your signed-in app read or change your own data.

How long we keep it

• Reading data and saved lines: until you delete your account.
• Feed events: about an hour. The short list of recent cards: up to 90 days.
• Synced imports: until you delete them or turn sync off, or 30 days after Premium ends.
• Daily AI and read-aloud counters: used to apply each day's limits, and deleted with your account.
• Purchase records (store transaction IDs and subscription status): as long as we need them for tax, accounting and refunds, even after you delete your account.
• Server logs kept by Google Cloud and Cloudflare: for limited periods, for security and reliability.

Deleting your data

In the app, go to You › About › Delete account. This deletes your account and its data from our servers (synced reading data, saved lines, study items, synced imports, usage counters and your recommendation profile) and from your phone. The app then starts fresh with a new guest account.

Deleting your account doesn't cancel a subscription. Cancel it in your App Store or Google Play subscriptions. We keep the purchase records described above.

Uninstalling the app removes the data on your phone, but not the synced copy. Because guest accounts can't be signed back into after an uninstall, please use Delete account before you uninstall. If you can't, email privacy@readkelda.com and we'll help.

Your rights

Depending on where you live (for example, under the GDPR in the EU and UK, or under California law), you may have the right to access, correct, delete or export your personal data, and to object to or restrict how we use it. To use any of these rights, email privacy@readkelda.com. Because the app uses guest accounts, we may need details from your app to find your data. You can also complain to your local data protection authority.

We process your data to provide the app you asked for (contract), to keep it secure and improve recommendations (legitimate interests), and to meet legal obligations such as tax records.

Children

Kelda isn't directed at children under 13, and we don't knowingly collect personal data from them. If you think a child has given us personal data, contact us and we'll delete it.

Changes to this policy

If we change this policy, we'll update the date at the top. If a change is significant, we'll tell you in the app.

Who we are and how to reach us

Kelda
Privacy questions: privacy@readkelda.com
Everything else: support@readkelda.com