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.

Features:

• Peer-to-Peer — There's no signup or account. 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 — 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 over the internet or on a local area network (LAN).
• Encrypted file transfers!
• Inline images, including animated gifs.
• Full Unicode and emoji support.
• Industry-standard AES-128 encryption.

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.

Screenshots: