Advertisements are placed by telling advertisers who you are for more accurate targeting. If you are not paying for the service, expect that the service is being funded through other means - in most cases, via advertisements. The likelihood of being acquired by a for-profit company is almost impossible! Private, Ad-free, Tracker-free Signal is owned by a non-profit foundation, Signal Foundation.

Telegram is owned by a Russian entrepreneur. Facebook Messenger and WhatsApp are owned by Facebook. Most popular messaging services are owned and controlled by for-profit companies. You can communicate with practically anybody who has the Signal application, as long as you know their number (BTW, Signal cryptographically hashes the phone numbers and stores it locally on your devices, not on Signal’s servers). Signal is available on all major platforms - Windows, Linux, Mac, iOS and Android. Viber, which uses the same open source Signal protocol for its E2EE, is not open source - as of my last check, their website does not have a link to their source code repository. Heck, all of the Signal software is open source! Some messaging services, like Telegram, claim to have E2EE, but their encryption protocol is *not* open (they keep it to themselves, so you take their word that it is secure). Not all popular E2EE messaging services are the same, but Signal is the one that has an open source encryption protocol, i.e., anybody can check the code and audit it.

Some messaging services (Telegram) require you to explicitly turn on/enable E2EE before you send a message - it is not on by default, nor is it always on! Open Source By default, all messages sent and received using Signal are end-to-end encrypted (E2EE), and it is always on - not some feature that you need to turn on or enable.

Who is signal messenger owned by