Apps connect to unknown IP Thanks to Little Snitch I've noticed that a lot of apps installed on my MacBook (El Capitan with latest updates) connect to an IP address in The Netherlands (23.74.205.239, registered with Akamai). As I couldn't find any more info on this I am wondering what to do?

So far I've blocked the IP on the system level and scanned my system with "MalwareBytes" without any problems. Strangely enough all that seems to happen is a connect but no data transfer (according to Little Snitch, with blockage of IP temporarily disabled). There is also no clear heuristic of which apps connect, the only thing: native Apple apps (iTunes, ...) are not affected. But if an app connects it does so with every start.

I am starting to worry because a few days ago I got a security notification by Cloudflare while accessing a website.

I am really curious what to make of all of this, and would appreciate any help or suggestions.
As Tetsujin mentioned in the comments, Akamai is simply a content delivery service with servers &amp; data centers around the world. The advantage to developers and companies is they get to access the closest server to your location for their ads or app content. 

Many ad networks use Akamai to get their ads and apps that use analytic services use them to get/send their data.  I'm about 99% sure there's nothing for you to worry about regarding the connections. You ran Malwarebytes and it said it didn't notice a problem and that's good.