Underpass

Underpass
P2P encrypted file transfer & chat

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.

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

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.

Features:

Peer-to-Peer — Underpass does not connect to a third-party service.
Your Mac or iOS device makes a direct network connection to another Mac or iOS device.
Privacy — There's no signup or account.
Underpass does not request your phone number, email, contacts, or any other personal information. You don't even need to use your real name.
Communicate securely over the internet or on a local area network (LAN).
Ad hoc peer-to-peer wifi networks too.
File transfers of any file type!
Inline images, including animated gifs.
Unicode text and emoji chat.
Industry-standard AES-128 encryption.