Element.io - Secure messaging app with strong end-to-end encryption, advanced group chat privacy settings, secure video calls for teams, encrypted communication using Matrix open network. Riot.im is now Element.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
ChatSecure - ChatSecure is a free and open source messaging app that features OTR encryption over XMPP.
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
Otr.to - A secure peer-to-peer chat in your web browser.
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.