It's been a very very long time I touched anything Java so excuse my ignorance. I know there are many Enterprise, internal Web Apps that uses Spring. But are there any web companies built their SaaS or Consumer Web App on Spring, that is at the scale of Shopify and Github?
Most companies at that scale don't use a single framework or even language but there's probably more Spring at Amazon than RoR at GitHub, Stripe and Shopify combined.
Stripe doesn't use Ruby on Rails, they have a framework developed in house
Aliexpress and Udemy come right at the top of my mind. But there are quite a few more. (several German web-sites like Trivago). Spring Boot is used more outside the U.S. - Java is respected more in the rest of the world.
I couldn't immediately locate it, but there was a famous example of an Amazon property leaking its Java stack trace but since I can't locate it I also can't swear it contained springframework classes
Pretty sure Netflix uses a ton of Spring.
It's one of the most common frameworks in the industry across languages.