Anyone has experience with Fiverr UI/ UX and App developers or can recommend one?

Hey Guys,

im considering building an App but I want to create a prototype before investing a few thousands in the actual product. Therefore I thought Fiverr could be an good option. If anyone has experience or can recommend one, that be great. Also what I need to take care of? How can I make sure that he is not fooling me and can steal the idea, etc.

Thank you in advance!