For starters if your looking for fully automatic systems:
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I myself don’t use proxy’s as much as I would like too, and even I myself am trying to look for ways to fetch items, like group owned tshirts, and things. However for starting your search, the dev forum is an amazing place for resources. I don’t know how advanced you are in scripting, but I myself find the dev forum helpful, as long as you can understand how other people scripts work and making it your own.

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I talked about this a bit, but I just want to make sure you understand, as well as developing ways around it. If a player inventory is private, it simply will not work . People’s inventory must be visible to everyone, if you want an inventory api to work. You can use a datastore and store all the asset ids, for easy access, if a player joins with a public inventory, but then hides it.
Here are some good dev forum posts that I found with a little bit bit of searching, about using inventory api:
Dev forum posts
The following are how to set up a proxy:
https://devforum.roblox.com/t/making-a-proxy-for-roblox-using-nodejs/1392622
Some sources about what your trying to do:
[OUTDATED] - But might still be useful, Roblox Inventory API Tutorial
[OUTDATED] Again Ik - But still might help, getting players inventory
When I say “outdated” they sadly are. Any post you find that using roproxy.com, in the url will not work, as the developers have stop supporting it.
These are just a few though, but if you do a search, you can find so many! Here might be a a couple key word searches: “How to make my own proxy roblox”, “How get get items from a players inventory”, “How to access roblox.com through https service”.
- Although setting this up might be a bit complex, I can atleast write it down on paper with what we want to do.
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We will want to use https://inventory.roblox.com/docs#!/Inventory/get_v2_users_userId_inventory_assetTypeId to fetch every item from a persons inventory.
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Then filter through each item, With
MarketPlaceService:GetProductInfo(AssetID)to check ifCreator.CreatorTargetIdmatches theUserIdof the player. If it does, we will check if it is a limited item. -
If it makes it through all of that, then we will post it, for other players to see!