warp is described as 'Secure and simple terminal sharing that lets you share your terminal with a simple "warp open" command. It's not a terminal client at this point, but simply multiplexes stdin/stdout to raw ptys between host and clients' and is an app. There are three alternatives to warp for Mac, Linux and Raspberry Pi. The best warp alternative is Upterm - Secure Terminal Sharing, which is both free and Open Source. Other great apps like warp are tmate and Assist.app.
Upterm is an open-sourced solution for sharing terminal sessions instantly over the public internet via SSH tunnels. It is good for
tmate is an instant terminal sharing software fork from tmux. Tmate can use as daemon, and you also can host your own server.
Assist is a service for remote teams letting users instantly share their terminals from anywhere.
