Ask HN: E2E Encrypted Messaging App that doesn't reveal phone number?

Use one that's not tied to a phone. Matrix comes to mind, may not satisfy your requirements though.

The free version of Wire (https://Wire.com), from the creators of Skype, Opus codec, WebRTC and IETF MLS, https://datatracker.ietf.org/wg/mls/about/.

Email is sufficient, it requires neither phone number nor contact sharing.

There is an app called Session which I think uses the Signal protocol under the hood. It doesn't depend on phone numbers at all.

https://getsession.org/

It hasn't received much attention since being purchased by Zoom, but Keybase still works fine. You get other handy things like encrypted file sharing and git repos, too.

Briar looks very interesting. Allows encrypted messages over Tor, WiFi, or Bluetooth (threat model is a communications-hostile environment/government).

https://briarproject.org/

Sounds like you already know the solution: treat your phone number as disposable. Get a new eSIM anytime you feel you want a refresher. It costs nothing, a dollar or two a month for prepaid. Turn it on only when you need to verify.

With Threema[1] you don't need to reveal a phone number. Great app love it, just doesn't have the userbase to drop WhatsApp. Paying for a messenger is asking too much apparently.

[1] https://threema.ch/en

If it’s for person-to-person chats (and not group chats), I’d recommend Telegram’s secret chat feature. Unfortunately, it’s tied to a single device (the one you start it on) and doesn’t sync across devices. You can also look at Matrix, which needs improvement in its UX but allows signing up with an email address.

Others have recommended Wire, which I’ve used for a few years until about two years ago. It doesn’t require a phone number, and an email address is sufficient. All chats are end-to-end encrypted and sync across all your devices (older messages sent before setting up a device wouldn’t).

There are some drawbacks to keep in mind with Wire: the company doesn’t care much about the non-enterprise segment. One of the side effects is that there is no way to export your chats (say, in text or HTML format) if you later decide you don’t want to use it anymore. You can only backup and restore chats on to the Wire app (and that also seemed to be platform specific when I checked it a few years ago). This means being locked in if you want access to the content. On the other hand, Telegram allows you to export chats so that you can have the content in readable form (say you decide to delete your account and save this beforehand). Wire also has a somewhat clunky Electron based desktop app (and you’ll know it’s Electron when you use it).

Another plus point for Telegram, which I haven’t seen in other apps that use a phone number: you can decide not to expose your account on Telegram to anyone who has your numbers in their contacts list (and allow only those you have on your contacts list to know, if you wish).

https://jami.net/ open source and doesn't require a phone number.

When I was on dating apps in the city a few years ago I saw people using Wickr to keep their PII private. Haven't used it myself but google says it's E2E and username based. Was acquired by Amazon last year though.