It's important to know where chests are placed in Fortnite - Battle Royale. It gives you an massive advantage. You can remember every single spot but the easier way is to see them in this application.
The Fortnite map where you can see every chest.
Remember that chests do not spawn guarantated, so if you can't find a chest at a spot, you're unlucky, the next it will be there probably.
In the case that you want a normal Fortnite map you can use the switch in the upper left corner to show and hide the chests.