Privacy Policy

Castline is built to keep your work on your device. There’s no Castline account, no ads, and no tracking. This policy explains what stays on your device, what leaves it, and why.

Effective date: October 7, 2026 · Last updated October 7, 2026

1. Who we are

Castline (“we”, “us”) is made and operated by the Castline team. This policy covers the Castline app for iPhone and iPad, including its share extension and remote features, and this website, getcastline.app. If you have questions, email [email protected].

2. No account needed

You don’t sign up or sign in to use Castline, and we never ask for your name, email address or phone number in the app.

When the app first talks to our server, it creates a random install ID. It isn’t based on your name, your Apple Account or your device, and it’s only sent to our server. We use it to count free AI scripts, to remember an access code you’ve redeemed, and to find data you’ve chosen to share so you can delete it. Deleting what you’ve shared gives the app a new install ID, and deleting the app removes it.

3. What stays on your device

• Scripts. Scripts you write, paste, import (text, RTF, PDF or Word files) or send to Castline from another app are stored in the app on your device. We don’t receive them. If you have Castline Plus, you can sync them through your own iCloud (see iCloud sync).
• Video takes. When you save a take, it goes to your Photos library. Castline asks only for permission to add to Photos. It can’t browse your library. The script on screen is never burned into the video.
• Audio recordings. Recordings made without the camera are kept inside the app with their script, until you delete them. They aren’t synced.
• Rewrites. Rewriting a script you already have uses Apple’s on-device model (Apple Intelligence, where your device supports it). The script doesn’t leave your device.
• Feedback and settings. Tips after a take, your reading speed and your settings are worked out and kept on your device.

4. Camera, microphone and speech recognition

Castline asks for these permissions, and you can change them anytime in iOS Settings:

• Camera: used when you record a take.
• Microphone: used to record your voice, and for voice follow, which listens so the script can keep your place.
• Speech recognition: used by voice follow, and to make captions for a take.
• Photos (add only): used to save your takes.
• Local network: used to find your other nearby devices for the remote.

Speech recognition is provided by Apple. Castline uses Apple’s on-device speech engine where it’s available, which may first download a language model from Apple. Otherwise it uses Apple’s classic recognizer and asks for on-device recognition when your device supports it. If on-device recognition isn’t available for your device or language, or it fails during a session, Apple may receive the audio for that session to recognize it on its servers. The same applies when captions are made. Apple handles that audio under Apple’s Privacy Policy.

We don’t receive your audio or the words you say. The one exception is the tester program described in section 6, which you have to join yourself.

5. Writing scripts with AI

Castline can write a new script from a short description. The first time you use it, the app tells you that your description is sent to xAI’s Grok and asks you to continue.

What the app sends to our server: your description (up to 600 characters), the type of script, the tone, the target length, your install ID and the app version. If you subscribe to Castline Plus, it also sends Apple’s signed record of your subscription, so our server can confirm it with Apple’s certificates.

What our server sends to xAI: fixed writing instructions plus your description, script type, tone and length. Your install ID and subscription record are not sent to xAI. Our request asks xAI not to store the response. xAI processes the request under its own terms and privacy policy.

What we keep: we don’t store your description or the script. For each request we record the plan, the model, the script length and type, whether it was refused, and how much it cost, plus a count of scripts written per install (free) or per subscription each month (Plus).

Please don’t put sensitive personal information in a description.

Other AI apps. If you choose to write with ChatGPT, Claude, Gemini, Grok or Copilot instead, Castline copies a prompt for you and opens that service. Anything you send there is between you and that service.

6. Voice follow diagnostics (optional)

Sharing is off by default. After a few voice follow sessions the app may ask, once, whether you’d like to share diagnostics to help improve voice follow. You can also turn it on or off in the app’s settings.

If you share diagnostics, after each session the app sends timings, pauses, how well words matched, how many words were heard (not the words themselves), your reading settings, your iPhone model and iOS version, and which microphone was used. It never includes your audio, your script, its title or what you said. Sessions are sent over Wi-Fi only (not cellular or Low Data Mode) and removed from your device once sent. We store them with your install ID, the app version and the time received.

Tester recordings. In beta (TestFlight) builds only, testers who confirm they’re 18 or older can also choose to share the audio of their voice while voice follow is on, their script and what the speech engine heard. Nothing is saved while reading is paused. This option isn’t offered in the App Store version.

We use this information only to improve voice follow. We never sell it or use it to identify you. To stop sharing, turn it off in settings. Delete what I’ve shared removes everything your install has sent from our server, turns sharing off, clears unsent sessions on your device and gives the app a new install ID.

7. iCloud sync

With Castline Plus, your scripts can sync through Apple’s iCloud (CloudKit) to your devices signed in to the same Apple Account. Sync is on by default for Plus and you can turn it off in settings. Your scripts are stored in your own private iCloud database, which we can’t access. Audio recordings aren’t synced. iCloud is provided by Apple under Apple’s terms and privacy policy.

8. Purchases and access codes

Subscriptions are sold and billed by Apple. We never receive your name, email address, payment details or Apple Account password. The app checks Apple’s signed transaction record on your device to unlock Castline Plus. That record (product, transaction IDs and dates) is also sent to our server when you write a script with AI, so we can confirm your plan and apply its monthly limit.

If you redeem an access code, our server checks it and remembers that your install ID has redeemed it, until the code expires.

9. Remote control and sharing takes

Remote. To use one of your devices as a remote for another, Castline uses Apple’s Multipeer Connectivity over local Wi-Fi and Bluetooth. Connections are encrypted and need no internet or account. Nearby devices running Castline can see your device’s name. Remote commands (like play, pause and speed) and the prompter’s status (script title, playing or recording, speed) pass only between your devices, never to us.

Sharing takes. When you send a take, Castline opens the iOS share sheet or the app you pick, such as a social app, and you post from your own account in that app. Castline doesn’t post for you or receive your login for those services. What you post is governed by that service’s terms.

10. Our server and service providers

Our server runs on Cloudflare. Like any web service, it receives your IP address with each request. We use it only to limit the number of requests per day, and that daily count expires after about a day. We work with:

• Cloudflare: runs our server and stores shared diagnostics, hosts this website, stores the launch email list, and routes email sent to our addresses.
• xAI: writes scripts from your description when you use AI writing.
• Our email provider: receives and stores email you send us.

Apple provides the App Store, iCloud, speech recognition, Apple Intelligence and Photos under its own terms and privacy policy.

11. What we don’t do

• We don’t show ads, and we don’t include advertising, analytics or third-party crash reporting tools in the app.
• We don’t track you across other companies’ apps or websites, and we don’t sell or “share” personal information for cross-context behavioral advertising.
• We don’t access your contacts or your location, and we don’t read your photo library.

If you’ve chosen in iOS Settings to share analytics with app developers, Apple may give us anonymized crash reports and usage statistics under Apple’s terms.

12. This website and email

getcastline.app doesn’t use cookies, analytics or third-party scripts. Our hosting provider may keep standard server logs, such as IP address, browser type and pages requested, to run and secure the site.

Launch list. If you sign up on this site to hear when Castline launches, we store your email address, which signup form you used, the page it was on and the date and time you signed up. Nothing else is kept with it. The list is stored on Cloudflare, our hosting provider. We use it only to send you emails about Castline’s launch and the Castline app, and we never sell it or share it for marketing. To be removed, reply to any of our emails or email [email protected] and we’ll delete your address.

To keep bots off the list, the signup form counts requests from each connection for a few minutes. It does this with a one-way coded version of your IP address, never the address itself, and those counts are deleted within about 20 minutes. Your IP address is never stored with your signup.

Email. If you email us, we receive your email address and whatever you write, and use it only to reply. Our Instagram and X pages are governed by those platforms’ policies.

13. How long we keep things

• Scripts and recordings on your device: until you delete them or the app.
• Scripts in iCloud: until you delete them on a synced device or from iCloud.
• AI descriptions and scripts: not stored by us.
• Script counts: the free allowance count per install is kept so the allowance works. Plus monthly counts expire after about 40 days.
• IP address request counts: expire after about a day.
• Access code redemptions: until the code expires.
• Shared diagnostics and tester recordings: up to 12 months, or until you delete them in the app, whichever comes first.
• Emails: as long as needed to answer you.
• Launch list: until you ask us to remove your address.
• Website signup request counts: deleted within about 20 minutes.

14. Your choices and rights

• Allow or revoke the camera, microphone, speech recognition, Photos and local network permissions in iOS Settings. If you turn off voice follow’s permissions, you can still scroll by hand.
• Delete scripts and recordings in the app, turn off iCloud sync, or delete the app.
• Stop sharing diagnostics and delete what you’ve shared from the app’s settings.

Depending on where you live, including California and the EU/UK, you may have the right to know what personal information we hold about you, and to access, correct, delete or port it, or to object to or restrict how we use it. We won’t treat you differently for using these rights. To make a request, email [email protected]. Because Castline has no accounts, we usually can’t link server data to a person. The in-app delete option is the most reliable way to remove what you’ve shared.

Where EU or UK law applies, we rely on: performing our contract with you (to provide features you ask for, like AI writing and subscriptions), your consent (diagnostics sharing, which you can withdraw anytime), and our legitimate interests (preventing abuse and keeping the service running). You can also complain to your local data protection authority.

15. Children

Castline isn’t directed at children under 13, or the minimum age in your country, and we don’t knowingly collect personal information from them. Sharing tester recordings requires being 18 or older. If you believe a child has sent us personal information, contact us and we’ll delete it.

16. Security, transfers and changes

The app talks to our server over encrypted HTTPS connections, remote connections between your devices are encrypted, and subscription records are verified against Apple’s certificates. No system is perfectly secure, but we limit what we collect so there’s less to protect.

Our service providers may process information in the United States and other countries.

If we change this policy, we’ll update this page and the effective date. If a change materially affects how we handle your information, we’ll tell you in the app or on this website first.

17. Contact us

Email [email protected].