Software

This is great news. Threema comes out on top on comparisons like this one, and it being closed-source was always a big downside. Another problem, however, is that it costs money. It's no issue for me to pay for it, but it's a barrier that makes it difficult for me to get my friends to use it. It's not reasonable to ask all of them to pay $4 for an app, especially if you're going to make it the only way you're reachable. On the other hand, I successfully got multiple friends to install Signal. I feel like that app provides the sweet spot between privacy / security and comfort.

Some other apps that I recommend, along with their unfortunate shortcomings:

• Tox – the shortcoming is that it's less reliable; it often takes a long time before a recipient receives a message.
• Briar – shortcomings: it's only available for Android, and lacks voice and video conversations.
• Rocket Chat – shortcoming is that it requires you to register an account, which not everyone's looking forward to.
• Session – a fork of Signal that does away with phone verification and automatically gives users a unique ID the way Tox and Briar do. This one has my interest the most, although it was not yet mature when I tested it earlier this year. Adding friends didn't go smoothly. Also, groups only go up to 10 users unless you host a server. I was unable to test it extensively.