If you’re a developer, then there is a very high possibility that at some point, you’ve needed to Google an issue and you encountered a StackOverflow question and got the help you needed.
Personally, I hit StackOverflow a few times per week, sometimes on a daily basis if I am tackling something I do not fully understand.
All of the developers I know use adblockers (I use uBlock Origin in Chrome) and by default blocking advertisements everywhere. But if there is one site that deserves to be whitelisted: it’s StackOverflow.
For general information about a wide range of topics, we have Wikipedia and for answering our development questions: we have StackOverflow.
They ask for no money, you don’t need an account to use it and the advertisements they do show are non-intrusive and tasteful (unlike a site like The Pirate Bay).
And above all else: StackOverflow don’t care if you block ads, although they would prefer it if you didn’t. The value of StackOverflow cannot be understated, it is the Wikipedia equivalent for developers and they deserve our support.