The difference between a policy and an architecture
A privacy policy is a pledge about what a company will do with data it holds. On-device AI removes the question: if your messages are never transmitted, there is nothing to hold. With Castmates:
- Replies are generated locally by a model running on your iPhone's chip.
- Conversations are stored only on your device, protected by your passcode and Face ID like your photos and notes.
- No account exists — no email, no profile, no identity to attach chats to.
- No message content is ever sent anywhere. The app transmits only anonymous, aggregate usage stats.
- It works in airplane mode — the ultimate proof that nothing depends on a server.
Why private AI chat matters
People are more honest with AI chat than with any social app — you vent, confide, flirt, and improvise stories meant for no one else. That is exactly the kind of data you don't want sitting in a server log, subject to breaches, subpoenas, policy changes, or a future acquisition. The safest place for an unguarded conversation is the device in your hand.
Private, but not shallow
Privacy is the foundation, not the whole product. Castmates is a character roleplay app with 32 hand-crafted characters across 8 genres — they narrate scenes, stay in role, and remember your story across sessions. You can also build unlimited custom characters with Pro, from persona to opening scene. All of it inherits the same guarantee: it happens on your phone and stays there.
Start free, no strings
The free plan is genuinely anonymous: 10 messages a day, the full SFW cast, one custom character — and since there's no account, "signing up" isn't even possible. Upgrade to Pro through the App Store if you want unlimited messages; Apple handles the payment, and Castmates still never learns who you are.