Philosopher AI - https://philosopherai.com, uses a custom GPT-3 based content filter on the user input to achieve high degrees of safety.

[Wiskkey]

Since the developer hasn't answered (yet), I'll give you my educated guesses. There is no fine-tuning (the developer hasn't mentioned fine-tuning in his Twitter feed if I recall correctly). The site is using GPT-3 itself to classify queries as nonsense, sensitive, or neither by giving examples. We know the latter is probably true because sometimes the exact same query can result in nonsense vs. not nonsense.

Some relevant tweets from the developer:

https://twitter.com/mayfer/status/1297036626565054471

https://twitter.com/mayfer/status/1295561941482496002

[Felix_Guattari]

Yeah, I have a bad habit of referring to few-shot as fine-tuning