Sagebath Check this out! https://paste.ente.io/ for my someone an encrypted, secure, private message with no need for an app nor an account.
NoahRaketic A dynamically loaded web app cannot be considered secure for sensitive information (e.g. "keys" as is mentioned on the linked page). There is no verification outside of TLS that you are receiving trustworthy code by the developer.
Sagebath NoahRaketic True, it shouldn't be used for top secret things, but it's likely more secure and at least keeps it away from your phone network provider.