Well, I will no doubt get chided for speaking more technically than most monks here do. (BTW: Just because you ordain, you can’t “unsee” your Computer Science Degree, especially considering Internet Culture has regrettably become culture itself, pretty much. All I can do is try to integrate my past in a way where it doesn’t overpower me, which I’ve actually gotten pretty good at. Meaning plenty of meditation, sutta reading, etc.
From MN 101:
Through active striving they become dispassionate towards that specific source of suffering,
Tassa tassa dukkhanidānassa saṅkhāraṁ padahato saṅkhārappadhānā virāgo hoti—
and so that suffering is worn away.
evampissa taṁ dukkhaṁ nijjiṇṇaṁ hoti.
Through developing equanimity they become dispassionate towards that other source of suffering,
Tassa tassa dukkhanidānassa ajjhupekkhato upekkhaṁ bhāvayato virāgo hoti—
and so that suffering is worn away.
evampissa taṁ dukkhaṁ nijjiṇṇaṁ hoti.
That’s how exertion and striving is fruitful.
Evampi, bhikkhave, saphalo upakkamo hoti, saphalaṁ padhānaṁ.
Alright? Disclaimer is hereby given.)
Firstly, the big-name computer security experts of the world should be heeded in their recommendations, when it comes to selecting such a crucial app. A very tough act to follow in this field is Bruce Schneier. He recommends Signal topmost. When you visit the signal.org website, this Titan (in his respective fiend) is right on the front page, and I invite you to take a good long look at his facial expression, letting it sink in. The unintelligent will scoff at this facial expression, and the intelligent will find accurate meaning there.
The way to cut through the muliplicity of choices is to humble yourself and listen to an expert. The expert Subharo? No, the expert Bruce. Let me give you an analogy. You have 10 friends. None of them are qualified Engineers. They all offer you their technically amateur advice, which sounds on the face pretty good, each in its own way. Your friends aren’t idiots, after all. But then along comes an actual Engineer, with an actual degree. His advice surpasses all 10 of your friends easily. Why? Because he’s actually trained for years in this area, and knows many subtleties and nuances which aren’t intuitive to any of your 10 friends. What all 10 of your friends suffer from is the Dunning-Kruger effect. It’s an easy mistake to make.
Secondly, I’ve tried several apps myself, doing probably like 30x more research than the average person would. I couldn’t find any perfect app, providing everything I wanted. Signal was the best I could come up with. Even without Bruce’s recommendation, I would have arrived at Signal. It’s reassuring to know that Bruce Shneier and I happen to think alike when it comes to Signal.
Can I guarantee that Signal will be the best app forever? No. But it’s what I would recommend today, and its future seems pretty solid (for the forseeable future, as best I can tell). In fact Signal has one disadvantage, compared to WhatsApp, see here.
Thirdly, the Desktop client for Signal is good. Any app which works great on a smartphone, but poorly on the desktop doesn’t cut the mustard for me. WhatsApp has a poor desktop experience, last time I checked, BTW.
Fourthly, it has good Linux support, which I use. Yes, only 2-3% of Desktops on Earth are linux, but you’d be surprised how many Buddhists use Linux! It seems like way more than 2-3% to me (yes, this is anecdotal).
Note: I’ve got most of my friends, and all of my family on Signal now.
PS: I wish I could recommend Wire, but I think that people who use the free plan will find their service downgraded after about 6 months or so (where message delivery mysteriously gets very sluggish), and find themselves craftily being levered into paying for the monthly premium plan service. That’s exactly what happened to me. Any such “freemium” service should be similarly mistrusted.