Flippa always recommends completing thorough due diligence before accepting a bidder on your auction.
While Flippa doesn't specifically require it, one of the best practices used by our top sellers is having a videocall and/or screen sharing with the other user.
You can also share screens to offer a live walkthrough of how the site or app works, show your live financial and user traffic details, and get a better idea of a user's veracity among other things. As with most things in life, your gut instinct is usually correct.
Three of the top technologies for videocalls and screen sharing are Apple's FaceTime, Google's Hangouts, and Microsoft's Skype.
While Flippa can't offer technical support for these technologies, here are some quick links to help you get started: