Can anyone recommend an alternative that doesn't train on user data?

If you want to be 100% sure you need to run/use a local LLM.

Also it seems that this data retention/training does not apply to the API.

I think both Anthropic and OpenAI do not train on enterprise data, so an enterprise account maybe.

Mistral doesn't seem to train on user data for the non-free models, but you can opt out on the free models.

https://help.mistral.ai/en/articles/347617-do-you-use-my-use...