Until very recently I worked there, and at once point I dug quite deeply into the company to see if I could find if it was still in use. I couldn't find documents referencing its present existence, packages to install it, or anything else, so I'm pretty certain that it's not in use.

There are three VIPs actively being used to load balance MongoDB traffic as of this moment.

The docs you likely found on the wiki are dated, but MongoDB is definitely being used in Enterprise Engineering.

Source: I'm currently on the EE traffic team.

It's difficult to make accurate blanket assertions about large technical organizations, which Facebook certainly is.

I am amused by the downvotes that my previous comments received.

Ah yes, but am engineer at Facebook installed it on his work laptop once

It’s certainly not used for any mission critical apps. Facebook’s stack is pretty well known. They’ve been using sharded MySQL for a while now. Instagram started on PostgreSQL but I believe has switched to Cassandra.

> mission critical apps

Thanks for the clarification.

As an example: would you consider the backend software stack that manages physical access to the campus 'mission critical'?

Ubiquity Edgerouters' management interface has a MongoDB backend and I have one on my desk at work, but I would not consider that I run "MongoDB" to provide services for my customers.

In much the same way I wouldn't say that my site is powered by Microsoft Excel; but you can be sure Microsoft Excel is used in my company.

I think they mean for first party backend tools. For example at my job I would say we use react in production - not on the frontend, but only for an internal warehouse application interface, nobody outside can use it but it's vital to our business, and we're the ones who built the application.

I would not. Facebook.com still operates with or without that system. Especially now with COVID-19, I’m sure it’s not being used at all.

Mission critical - essential for operating Facebook.com

> I’m sure it’s not being used at all

Is is a company wide system? Its all fun and games until the cooling in a dc starts to have issues and the facilities team can't gain access because....mongo... ?

Sure, that's mission critical (ish), but it's not really what people think of when they think of Facebook. It's not millions of posts per second, ultra scalable whatever.

Disclosure: I worked at Facebook, but not in that department, or anywhere near any MongoDB.