Initially for my own use, I created an open-source web server that displays account information from the API to make relevant information more accessible. The most complex page lists available achievements that can be sorted and filtered by different criteria. All pages provides links to the Wiki for items.
Other pages provide information across all characters, e.g., when trying to find which character has a particular item in the inventory without having to log in to all characters.
Equipment. Lists the equipment of all characters.
Inventory. Lists the inventory of all characters grouped by item classes.
Wallet. Displays the contents of the wallet.
Bank. Lists the content of the bank grouped by item classes.
Materials. Lists materials stored in the bank.
Skins. Displays all skins available in the game with the ones not yet unlocked grayed out.
Recipe Skins. Displays locked skins for which the recipe is known.