Most games these days have APIs - why haven’t you followed suit?
D3 is from 2012. Does D4 and similar games have anything like what you ask for? If you’re new to the game everything can be somewhat confusing. There are websites with guides to the game.
I’m a software developer - it would not be impossible to build web services to extract stuff out of a data model even if game originated then. They want too much for D4. Take a look at Eve Online -that’s likely older - they exist for that.
The only thing resembling something like that is the D3 planner section on maxroll’s D3 site, where you can import a hero profile and make all sorts of calculations (as far as I know). Apart from that Blizzard is quite protective about their software. Many years ago there was a third party software that made it possible to get a complete overview of all characters and everything in their inventories without going through them one by one individually. I believe there are still some hacks around and about (like map hacks and botting). These things are strictly forbidden and can result in account bans… And they are not what youre looking for. (Neither am I of course!).
Hello:
There are APIs available for D3… I do not know whether a hero inventory or the chest are accessible from those.
Blizzard provides 2 special forums for APIs, one for discussions between developpers and another for reporting bugs. There is an introductory post here:
The Diablo III documentation is here:
https://develop.battle.net/documentation/diablo-3
This page provides some high level info on what type of data are available. For D3, it says:
Diablo III: player hero information, character class and skill information, and crafting recipes.