HTTPS
Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol (HTTP) for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protocol is encrypted using Transport Layer Security (TLS), or, formerly, its predecessor, Secure Sockets Layer (SSL). The protocol is therefore also often referred to as HTTP over TLS, or HTTP over SSL.
.app (gTLD)
.app Domains are, according to Gandi.net and other Resellers, "a security-focused space, meaning that HTTPS is required for all websites."
This is accomplished by having the .app top-level domain included on the HSTS preload list, making HTTPS required on all connections to .app websites