That I can talk about publicly? Probably https://lightningai.com/.

Their control panel drives companies' entire online marketing operation - creative, targeting, performance, and more - across multiple advertising services. That's a whole lotta UI. Their back end drives the advertising platforms' APIs (eg Google and Facebook), and it all hooks into great big machine learning operations that run on big beefy servers out in EC2. Not just a pretty CRUD app, that's for sure.

(Unfortunately, they know what their services are worth, so I can't just point you at a live demo ;) )