Doesn’t have to be for coding, but just apps you’ve found useful; 
I think this is great:
The thing I like most about it is how it lets you mimic various iPads - I know Chrome does too, but with this you are using (I presume anyway) the Safari engine, so it should be a very authentic experience and pretty much the same as using any of those devices directly. Well worth the money 
Built in Notes app is also one of my most used apps - it’s so easy working on something and easily being able to switch to it from your computer to your iPad or even iPhone.
Taking notes with the Pencil could be better tho. I am forever tapping just to the right of a word (because I want it the cursor there) but it just does weird stuff, like highlight the word! Also I think they could make it a lot smarter, for example when you’re typing something like <div... it should be smart enough to know you want to type things like center and it for not to be changed to centre! But maybe that’s a rant best saved for another thread 