ChatSecure is described as 'Free and open source messaging app that features OTR encryption over XMPP. You can connect to your existing accounts on Facebook or Google, create new accounts on public XMPP servers(including via Tor), or even connect to your own server for extra security' and is a popular instant messenger in the social & communications category. There are more than 100 alternatives to ChatSecure for a variety of platforms, including Android, iPhone, Windows, Linux and Mac apps. The best ChatSecure alternative is Signal, which is both free and Open Source. Other great apps like ChatSecure are Telegram, Element, Tox and SimpleX Chat.