You could go around to website after website and check each app specifically. That would only take some people a few days!!
You could also go over to the The RoaringApps compatibility table and take a look at all the apps at once.
Go ahead and set the display to 100 records. It’s easier to look through them that way.
Bring up the Legend by clicking “Legend”. What you want to see is that wonderful green. If you see blue, you may have to go to the vendor’s website and look.
If you want to find a specific app, you can use the search to find the program in question.
Now, you will see there are a lot of “No Data” when you look at the “El Capitan” column. However, this is a crowd-run site and it is updated all the time.
So check back often.