Duck.ai is a saas, I can never be 100% sure that information sent to it is private, the only way to use an LLM privately is to run it locally.

Do you think it really doesn't train on your data?

That is very unlikely, duck.ai doesn't brew it's own in-house AI, they run models made by third parties like Mistral, Facebook and openAI.

As far as non-local LLM inferencing goes, I think duck. Ai offers the most privacy-friendly service.

While it's impossible to warranty privacy, you can warranty anonymity, because duck.ai is accessible over tor.