How many companies use Google AdWords?

How much do web companies use Google's software stack?

• There's a tendency at Google to write in-house software for our unique scaling needs (both engineering/software processes and hardware). A good number of these have been open sourced and made available to the developer community as well, the likes of GWT, the Closure framework, Protocol Buffers, etc. There have also been published papers and talks on internal tools such as Spanner, BigTable, and Dremel. I'm curious - how many companies actually make use of Google developer technologies? Is Google training its people to use systems that they will never encounter at another job? What's stopping other companies from leveraging the open-sourced software that is available?

• Answer:

  Other companies do use some of Google's Open Source software and ideas, including software modeled after papers published by Google (the Apache project basically replicates the stack: Hadoop, HBase, Drill...). I see Protocol Buffers used a lot. GWT is probably considered a bit weird and old but AngularJS is aopted everywhere these days. On top of that, a lot of the Google stack itself is accessible via its Cloud offering (App Engine, Compute Engine, BigQuery...) and people use that. EDIT: Looks like I resurrected an old question :) The OP works at Square now. No idea why Quora proposed me to answer this.