PrismCipher For Chrome can be used to encrypt information over the following services:

  • Google Gmail
  • Yahoo! mail
  • Outlook on the web
  • ProtonMail
  • Slack direct messages

PrismCipher should work flawlessly in any Chromium browser (blink engine), such as:
   Ungoogled Chromium

Porting this over to a non-Chromium browser environment such as FireFox (gecko) or Safari (webkit) does not appear to be trivial. It’s planned, but won’t happen soon.