P2P encrypted file transfer & chat
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Peer-to-peer file transfer and chat app for Mac and iOS, with end-to-end encryption for complete privacy and security. Underpass can communicate between your own Apple devices or with another Underpass user.

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macOS 10.12 - 10.15 and macOS 11
Sierra, High Sierra, Mojave, Catalina, Big Sur
Universal Binary: Intel, Apple Silicon

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iOS 11 - 14
iPhone, iPad, iPod

Support: For documentation and contact information, see Underpass Support.

Who: An independent software developer on Apple platforms, Jeff Johnson is the creator of Underpass and 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.