P2P encrypted file transfer & chat
By Jeff Johnson
Underpass is a peer-to-peer file transfer and chat app for iOS and macOS that features end-to-end encryption for complete privacy and security. Underpass can communicate between your own Apple devices or with another Underpass user.
Support: For documentation and contact information, see Underpass Support.
Who: Jeff Johnson, an independent software developer on Apple platforms, is the creator of Underpass and also the web browser extension StopTheMadness. Jeff was a longtime engineer at Rogue Amoeba Software. Before that, Jeff worked on apps such as Knox (originally developed by MK&C, later sold to AgileBits) and the open source RSS reader Vienna.
Why: Read the story of why I wrote Underpass and why you should use it.