While Psiphon Pro offers faster speeds via a subscription (which supports their mission), the free version of Psiphon is legitimate and functional. It is funded by ads and limited speed, but it is secure. You can find the genuine open-source client directly on their official website or GitHub repository.
If the website is blocked in your country, you can send a blank email to get@psiphon3.com to receive a download link. 2. Understanding "Psiphon Pro" vs. Free psiphon key free