Why people are looking for a CHAI alternative
CHAI is a popular cloud app for chatting with user-made bots (about 287,000 ratings on the US App Store). In reviews posted on 4 and 5 October 2026, a large share of the one-star reviews say the same thing: free daily messages were replaced by pieces you pay for, and some reviewers say memory is paywalled even on the top plan. A few also mention chats being deleted after a period of inactivity. These are reviewer reports, not something we've verified ourselves, and CHAI may change its plans again.
Castmates vs. CHAI
| Castmates | CHAI | |
|---|---|---|
| Where the AI runs | On your iPhone | In the cloud |
| How free use works | 30 messages a day, no currency | Free tier plus paid "pieces" per message, and an Ultra plan (App Store listing, Oct 2026) |
| Works offline | Yes, after the model download | No (cloud app) |
| Bots to chat with | A curated cast of 35, plus your own custom characters | Build and share bots with other users |
| App size | 34 MB app plus a ~2 GB model download | 186 MB |
| Phone requirement | iPhone with 6 GB RAM or more | Not specified on the listing |
Sources: both App Store listings, checked on 7 October 2026. If something in CHAI's row is out of date, tell us at [email protected] and we'll fix it.
The honest trade-offs
- You need a recent iPhone. Castmates runs its model on the phone, which takes an iPhone with 6 GB of RAM or more and about 2 GB of free space. On an older phone it won't work well, and a cloud app is the better choice.
- No community library. CHAI's strength is the huge range of bots people have made. Castmates has 35 written characters and a builder, nothing to browse beyond that.
- A smaller model. A model that fits on a phone is smaller than what a data center runs. We tune the characters to stay in role, but long chats can still drift.
What happens when their servers go down
A cloud app needs its servers, its login and your connection to be working at the same moment. When any of them fails, the chat stops. Castmates downloads its model once (about 2 GB, over Wi-Fi is easiest) and after that there is no server in the loop for CHAI to take down. It works in airplane mode, on a train or when the CHAI app is having a bad day. The first download does need a connection, and Castmates can still crash or be slow on an older phone like any app.
What you get instead
Every reply is generated on your iPhone, so your messages aren't sent to a server, there's no account to make, and it works in airplane mode once the model is installed. The free plan gives you 30 messages a day with the full cast and one custom character. Pro lifts the daily limit and the character cap.