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#889 Identifying Steam Items

Posted by Dr. McKay on 20 May 2016 - 12:40 AM

Sometimes it can be a little confusing to identify a specific item in the Steam economy. There are several different types of IDs present in one particular item, and a lot of vague terminology. This guide aims to clear all that up for you.

For starters, the "official" term for a Steam item is an asset. When I say a "Steam item", I mean a particular copy of an item. I'm not referring to the item's definition, name, image, or anything. I'm referring to a specific, unique copy of the item.

In a general sense, every item on Steam must be owned by an app. An "app" is a game, software, or whatever on Steam. Every app has its own unique AppID. You can find a particular game's AppID by going to its store page or community hub and looking at the URL. For example, TF2's AppID is 440 so TF2's store page can be found at http://store.steampowered.com/app/440. CS:GO's is 730, Dota 2's is 570, and so on. Note that Steam Community items, Steam gifts, and other "Steam" items are owned by the "Steam" app, which has AppID 753. To identify an item, you'll need the AppID of the game which owns it.

Of course, the AppID alone isn't enough. You also need two other IDs. Have you ever noticed how some games have multiple inventories, which appear in a drop-down list? An example is the Steam inventory, which has sub-inventories for "Community", "Gifts", "Coupons", etc. These "sub-inventories" are called contexts, and each context has its own context ID. If a game doesn't have a drop-down menu to select a context, that doesn't mean that it's without contexts. That only means that it has one single visible context. That single context still has an ID. For all current Valve games, the context ID for the publicly-visible context is 2.

Context IDs can be a bit tricky. It's entirely up to the game's developer to determine how they work. For example, Valve games take the "single shared inventory" model in which there's one context ID which is shared by everyone. Under this model, an item belongs to one particular context and never leaves that context. Consequently, the item's context ID never changes. It is, however, possible for game developers to create contexts in any way they choose. For example, Spiral Knights uses the "per-character inventory" model in which everyone who plays the game has their own context IDs for their characters. Creating a new character creates a new context ID. This means that when an item is traded between users, its context ID will change as it moved out of a particular character's inventory.

Those are the two different types of "containers" in the Steam economy. Apps own contexts, and contexts own assets. Every asset on Steam has, in addition to its AppID and context ID, an asset ID which is guaranteed to be unique inside of a given AppID+ContextID combination. Notice that this means that asset IDs are not unique across all of Steam. They aren't even unique across a particular app. They are only unique inside of a given context. For example, there could be two items with asset ID 1 in the same game, as long as they have different context IDs. An item's asset ID may be referred to as "assetid" or just plain "id".

Context IDs and asset IDs are assigned by the game developer and can follow any pattern. They can change when traded or not. They may both be up to 64 bits in size. Consequently, Steam returns them (like all other 64-bit values) in JSON as strings.

Still following? All of what we've learned so far leads us to this conclusion: in order to uniquely identify an item, you need its AppID, its context ID, and its asset ID. Once you have these three things, only then can you uniquely identify it. In fact, this is how you link to a particular item in a user's inventory: steamcommunity.com/profiles/steamid/inventory#appid_contextid_assetid. Here's an example: https://steamcommuni...440_2_134161610

What on Earth are these "classid" and "instanceid" values though??
The observant reader may have noticed that there are two more IDs attached to a particular item which I haven't mentioned. These are the "classid" and "instanceid". These IDs are used to map an asset to its description.

What's a description? A description is what you need in order to actually display an item. An item's description contains its name, image, color, market_name, whether it's tradable or not, whether it's marketable or not, and more. There are many endpoints on Steam which return JSON objects representing assets that only contain the asset's AppID, context ID, asset ID, classid, instanceid, and amount. An item's amount is how big of a stack it is. Unstackable items always have an amount of 1. Stackable items (such as Steam gems) may have a larger amount. Stacked items always have the same asset ID.

What's the difference between a classid and an instanceid? Well in a nutshell, a classid "owns" an instanceid. The classid is all you need to get a general overview of an item. For example, items with the same classid will pretty much always have the same name and image. The instanceid allows you to get finer-tuned details such as how many kills are on a strange/StatTrak weapon, or custom names/descriptions.

You can turn a classid/instanceid pair into a description using the GetAssetClassInfo WebAPI method. Notice that the instanceid is actually optional: if you only have a classid that's fine, you just won't get finer details for the item.

Do note that it's possible for a game developer to flush Steam's asset cache entirely, which would change the classid/instanceid of every item. As of the time of this posting, I'm unaware of this ever having been done.

Name? Market Name? Market Hash Name? Halp?
Every asset on Steam has a name. Period. Without a name, there's nothing to show in your inventory. The item's name is the... (wait for it...) name property of its description (shocking, I know). The item's name may be localized if the game's developer has set it up to be.

Every marketable item also has a "market name". This name may be the same as, or different from the item's regular name. The item's market name is the market_name property of its description. This is the name that's displayed in the Steam Community Market when the item is up for sale. Why the distinction? There are some items which have value-affecting data that isn't in their name. For example, CS:GO skins have 5 different tiers of "wear", which isn't in their names. The wear tier is appended to each skin's market name however, so that the different tiers of wear are separated in the market. The market name may be localized or not, and may not exist at all if the item isn't marketable. It's up to the game's developer.

Finally, every marketable item also has a "market hash name", available under the market_hash_name property. This name is supposed to be the English version of the item's market name, but in practice it may vary. For example, Steam Community items prepend the AppID of the originating app to each item's market hash name, but not to the market name. The market hash name is never localized, and may not exist if the item isn't marketable. Again, it's up to the game's developer. You can view the Community Market listings for any marketable item using this URL formula: steamcommunity.com/market/listings/appid/market_hash_name. Here's an example: https://steamcommuni...upply Crate Key

Note that the Community Market has no concept of contexts. Consequently, market [hash] names are unique for a particular "class" of items per-app (and by extension per-context). This means that for marketable items, two items with identical market hash names will be worth roughly the same (with some exceptions, like unusual TF2 items).

Ask below. I'm happy to help!

  • Mole, Andrew, trzyrazyzero and 1 other like this

#497 Error sending trade offer (15)

Posted by danek on 05 April 2016 - 01:53 PM


What mean this error:


Error: There was an error sending your trade offer.  Please try again later. (15)


  • loyare74 and clisteri like this

#1537 Minimal code to stay logged in forever...

Posted by Dr. McKay on 06 August 2016 - 11:03 PM

That all looks fine to me. sessionExpired is only emitted when a request you make fails because you aren't logged in. It doesn't check automatically, it only checks whenever the library makes a request somewhere.


Starting a new confirmation checker without stopping the old one is just fine. It'll stop an old one if you call it while one is running.


I recommend updating to v3.23.1 if you're going to use webchat.

  • yellowish and klonaway like this

#143 TradeOfferManager v2

Posted by Dr. McKay on 03 March 2016 - 02:10 PM

Here's an idea. Three options for createOffer():

  1. manager.createOffer(steamID); // create an offer without a token. you can set it later
  2. manager.createOffer(steamID, token); // create an offer with a token
  3. manager.createOffer(tradeURL); // automatically extract the SteamID and token from the trade URL

  • Mole and PEPZ like this

#3947 Getting all comments/activity from a group.

Posted by Dr. McKay on 21 July 2017 - 02:44 PM

There's nothing in the module right now to parse comments.

  • drizz likes this

#3920 webSession expires, but loggin in again returns "Already logged on"

Posted by Dr. McKay on 16 July 2017 - 03:24 PM

  1. Cookies obtained from a CM are invalidated as soon as the connection drops. You should pause your queue when you get disconnected, and only restart it once webSession gets emitted after reconnection.
  2. No, I don't believe that would be a problem.

  • esteamer likes this

#3894 Check if a offer sent by the bot was accepted

Posted by Dr. McKay on 13 July 2017 - 09:37 PM

Listen for the sentOfferChanged event and see if the new state is Accepted.

  • Nacho likes this

#3778 addTheirItems add all items from a appID

Posted by Dr. McKay on 02 July 2017 - 05:29 PM

Fetch the inventory for only tradable items, then call addTheirItems with the raw array of items. I believe there is an example in the repo that does exactly this.

  • Nacho likes this

#3679 Error installing node-steamcommunity

Posted by Dr. McKay on 17 June 2017 - 10:09 PM

The npm name is just steamcommunity.

  • TomYoki likes this

#3517 offer.itemsToGive/Recieve.length Doesn't Exist

Posted by AlaDyn172 on 06 June 2017 - 03:30 PM

You made a typo, it's itemsToReceive not itemsToRecieve.

  • xLeeJYx likes this

#3411 GetOwnedApps & Steam Family Sharing

Posted by Dr. McKay on 21 May 2017 - 09:55 PM

Thanks. Looks like there's an expiry time in those packages which is being ignored. Let me take a look at the code.

  • Royalgamer06 likes this

#3261 Shared secret and Identity secret

Posted by jafix on 05 May 2017 - 03:39 AM

Go to the folder maFiles you should see some (depending on how many acounts are running on sda) .maFile files. They are all named like <steamid64>.maFile find the one you need and open it in your text editor. Just look through the file until you find shared_secret and identity_secret.

  • Enemtia likes this

#3162 Steam Rate Limits

Posted by Dr. McKay on 19 April 2017 - 08:13 PM

Some people are working on maintaining a list of rate-limits here: https://www.reddit.c...iki/rate-limits

  • Royalgamer06 likes this

#3153 Nothing fired after loggedOn event

Posted by Dr. McKay on 17 April 2017 - 07:51 PM

You're logging in anonymously, because you're using account_name instead of accountName.

  • Jinxed740 likes this

#294 [Question] New steam accounts and trade holds

Posted by Dr. McKay on 21 March 2016 - 09:14 PM

Any new Steam account will be unable to trade entirely for 15 days, since you need SG enabled for 15 days in order to trade.


A sentry file is how Steam remembers a "device" for Steam Guard. You'll get sent one when you login without one, and you should save it and use it for subsequent logins. node-steam-user does this for you.


You can't bypass the 15-day waiting period for Steam Guard. Trade holds (which last for 15 days) can be disabled by enabling the mobile authenticator. Once the mobile authenticator is enabled, after you wait 7 days, trade holds go away. You can wait out the 7 days at the same time as the 15 days.


So the quickest way to get a new Steam account tradable is to verify its email and immediately enable the mobile authenticator. Once done, it will be able to trade in 15 days.

  • spock likes this

#2225 How to Get All Item From CS GO

Posted by maraya on 07 December 2016 - 01:42 AM

thank you sir.

  • evirtual_dev likes this

#1788 relogin to steam

Posted by Dr. McKay on 23 September 2016 - 01:48 PM


  • GHOST likes this

#1587 A few Questions

Posted by Dr. McKay on 14 August 2016 - 02:22 PM

  1. Only Valve knows the answer to that, but out of the interest of everyone I'd avoid registering accounts super quickly.
  2. No idea.
  3. Not possible through steam-user at this time, but would be possible to implement. Couldn't give you a timeframe, though.

  • MrRobot likes this

#1566 Cannot read property 'escrowDays' of undefined

Posted by Dr. McKay on 11 August 2016 - 08:23 PM

You aren't checking the error. In every callback, if err is truthy, then there was an error and all other arguments are undefined.

  • KiTa likes this

#1171 Bots without apikey

Posted by darkwar1234 on 24 June 2016 - 03:47 PM

What will be if I just set manager.apiKey with value from my another account which is activated?

  • darkwar1234 likes this