MapHub is a standalone application for windows. There's many services out there - some paid, some free - that offer similar features, however, MapHub offers a premium experience:

- Customizable overlay (so the map is shown in overlay to your screen while you play )
- Social feature, as you and your friends can draw together on the map to discuss strategies or to teach/explain tactics/how to play). The overlay is also updated automatically.
- An editor to create and share your own maps in a native, fast viewer/editor allows a fast and responsive experience even with many POIs and screenshots on the same map over multiple layers
- Steam workshop native support to share maps with the community
- Maps once downloaded are offline and thus, you don't have to worry about not being able to access your maps in the future

Some features are certainly shared with other products and if you just need a lootmap sure, there are many websites out there! If you want more than just a lootmap, there's maphub! It's up to you to choose whether you need those or not :)