Truly offline, not "offline mode"
Some apps offer a cached, degraded offline mode. Castmates doesn't need one — offline is the architecture. The language model that writes every reply runs on your iPhone's own chip, so nothing about the experience changes when the connection drops:
- Full conversations — characters narrate, act, and stay in role, online or not.
- Full memory — story summaries and history live on-device, so characters still remember you.
- Full cast — all 32 characters and 96 scenarios are local after the one-time setup.
Where offline AI actually matters
- Flights. A long-haul flight is exactly when you have time for a long-form scene.
- Commutes. Subways and tunnels stop being dead time.
- Travel. No roaming data, no problem — and no surprise bills.
- Anywhere private. No connection also means no server on the other end reading along.
Offline is also private
An offline AI chatbot has a property no cloud app can match: your messages physically cannot be uploaded, logged, or used for training, because they never leave the device that generated them. Castmates adds no account and no profile on top — there is simply nothing tying your conversations to you.
Getting set up
Install Castmates from the App Store, download the on-device model once (~2 GB, Wi-Fi recommended), and you're self-contained from then on. The free plan gives you 10 messages a day with no sign-up — enough to meet the cast before a trip.