OpenPGP.js - A JavaScript implementation of the OpenPGP protocol.
keys.openpgp.org - An OpenPGP Key Server with verified emails and a focus on privacy.
Mozilla Firefox - Allows direct access to response data (though with a few caveats).
Libravatar - Universal email-based avatars.
js-md5 - A JavaScript implementation of MD5.
Internet Archive - Archives web pages.
Cloudflare - Provides a DNS-over-HTTPS JSON endpoint used for Libravatar's DNS-based federation.