A friend asked me why I might choose Signal over WhatsApp. It comes up every so often and this is what I said to her:

Cool question.

The biggest problem I have with WhatsApp is that it's owned by Facebook. Facebook get the metadata of WhatsApp communications whereas Signal have just announced clever tech where we won't actually have to trust their servers with our social graph.

WhatsApp is closed source, which means we can never really be sure what it is doing. Signal is free (as in speech and as in beer) software (open source) with reproducible builds so we can verify what code is running. It runs without using Google Play Services if you're willing and want to run a Google free phone, WhatsApp doesn't. Alternative clients should work on the Signal network, at least in theory (dunno if there are any yet), very unlikely with WhatsApp.

Enough to be getting on with? I realise a lot of this is kind of abstract and privacy geek stuff but I think it is worth bearing in mind that it is privacy and free software geeks who write the protocols that power both Signal and WhatsApp. I'd love to hear some counterpoints but I think that Signal is a very rare beacon of hope in an increasingly (?) closed and surveilled world.