Ask HN: Technology stacks of popular web platforms

I recently stumbled across the tech stack of Quora(http://www.bigfastblog.com/quoras-technology-examined) and Summify(http://www.bigfastblog.com/summifys-technology-examined) through hacker news and I found their insights on what technology they used and why, very helpful for my own SaaS project. I was wondering if there are more similar articles on other technology stacks. It would be very helpful for future developers to learn from the mistakes and choices of these big platforms.