This looks really good, I've used ccrypt (#1) for years as a simple Unix-y encryption tool to avoid the complexity of GPG (though this is symmetric encryption only so you need to have a secure way to exchange keys).

I just added a pull-request to allow the recipients flag to also be specified as a https:// or file:// URL - this is mostly useful to use the GitHub <user>.keys endpoint to grab user keys eg.

  ./age -a -r https://github.com/<user>.keys < secret

will encrypt using <user>'s GitHub SSH public keys.

#1 http://ccrypt.sourceforge.net

#2 https://github.com/FiloSottile/age/pull/43