Wire – encrypted voice, video and group chats; and works in a browser

On their Privacy page they put a check box for their entry in the comparison table for being "Open Source". And then they write:

> Our commitment to security is entirely verifiable — you don’t have to take our word for it. Wire uses open-source cryptography to encrypt all content. We made the source code for data handling available to the public under the GPL License. This means that anybody can review the source code.

This is very misleading. To provide verifiable security, the source code of the client software must also be open source, which it does not look to be. Because how else can you prove that the client software is also secure?

How are they making money ? I mean they say they are about 50. They need a ton of money to pay them.