Need Steam API help

[CockneyMan424]

I'm trying to get info on The Witcher 3 GOTY Edition from the API. When I use https://api.steampowered.com/ISteamApps/GetAppList/v2/ to get all the Steam apps, it says the app ID for this is 499450 but https://store.steampowered.com/api/packagedetails?packageids=499450 gives no info, instead you have to use https://store.steampowered.com/api/packagedetails?packageids=124923 but the ID 124923 isn't anywhere on https://api.steampowered.com/ISteamApps/GetAppList/v2/

[MalikQayum]

it can be confusing as to why this happens but the short answer is that what you are looking at does not have its own store page.

you are using the storefront api, and when the steam storefront does not have an app page for "499450", it won't return anything.

https://store.steampowered.com/api/appdetails?appids=499450

{
    "499450": {
        "success": false
    }
}

this means the "The Witcher 3: Wild Hunt - Game of the Year Edition" gives you another entry in the library. the appid, you should be looking for is not 499450 but 292030

{
    "appid": 499450,
    "name": "The Witcher 3: Wild Hunt - Game of the Year Edition"
}

{
    "appid": 292030,
    "name": "The Witcher 3: Wild Hunt"
}

https://store.steampowered.com/api/appdetails?appids=292030
this appid returns the packageids 124923

"packages": [
    68476,
    303242,
    124923
]

EDIT:
when using the storefront api, it is best to be getting your list appids from this interface IStoreService and then the method GetAppList instead.
https://steamapi.xpaw.me/#IStoreService/GetAppList