Google and Facebook did use the protocol - XMPP - for their instant messaging for much of the 2000's. So did What's App https://medium.com/@rajendra_5....

Any company that does build with Open Standards that work (I would say XMPP does) are bought by bigger companies and then folded into their strategy. Jabber.com was bougth by Cisco Systems in 2004. (I was briefly the CTO of that company. RedHat/Open Office/Java/My SQL are all Open Source products that lost momentum when larger companies bought the commercial company with most of the developers.

What's App used XMPP (Jabbers standard implementation) for through gaining 50 million users before they came up with their own protocol. https://medium.com/@rajendra_5...

Jabber was widely adopted throughout the 2000's. What's App started with it (XMPP is the Jabber protocol) for the first 50 million users, before they came up with they own system. Google, Apple and Facebook all used XMPP at various points in their instant messaging evolutions. This article is a good summary of What's App. https://medium.com/@rajendra_5... [medium.com] The standard spawned by Jabber is still flourishing here: https://xmpp.org./ [xmpp.org.] As for Jabber the application, it did not become widely used. The protocol that Jeremie spun out of Jabber has become an important interoperability over the years. Disclosure, I was the CTO of a commercial company (Jabber.com - acquired by Cisco Systems) that tried to commercialized Jabber itself. That was not working and the last thing I did as CTO was hire a team familiar with the IETF standardization process and propose XMPP as the standard.