Why people look for a PolyBuzz alternative
PolyBuzz is a cloud app: your messages go to its servers, and you chat with characters made by the community. It is free with in-app purchases and has hundreds of thousands of ratings on the US App Store. People who want something different usually mention one of three things: they'd rather not send private roleplay to a server, they want it to work without a connection, or they want a smaller, steadier cast instead of a huge catalogue. We haven't tested PolyBuzz's behaviour ourselves, so check its listing for current details.
Castmates vs. PolyBuzz
| Castmates | PolyBuzz | |
|---|---|---|
| Where the AI runs | On your iPhone | In the cloud |
| Works offline | Yes, after the model download | No (cloud app) |
| Account | None | Not specified on the listing |
| How free use works | 30 messages a day | Free with in-app purchases (App Store listing, Oct 2026) |
| Characters | A curated cast of 35, plus your own custom characters | Large community catalogue, plus voices |
| Age rating | 18+ | 17+ on the App Store |
| App size | 34 MB app plus a ~2 GB model download | About 260 MB |
| Languages | English | 27 listed on the App Store |
| Phone requirement | iPhone with 6 GB RAM or more | Not specified on the listing |
Sources: both App Store listings, checked on 8 October 2026. If something in PolyBuzz's row is out of date, tell us at [email protected] and we'll fix it.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, a cloud app is the better choice.
- Far fewer characters. Castmates has 35 written characters and a builder. There's no community catalogue to browse.
- English only. The app and its voice calls are English only for now.
- 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.
- iPhone only. There's no Android or web version.
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 PolyBuzz to take down. It works in airplane mode, on a train or when the PolyBuzz 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.