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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 2 others 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

#4199 Send/receive messages to/from non-friends

Posted by Dr. McKay on 23 August 2017 - 04:24 PM

You should be able to send messages to non-friends if you're in a group chat with them, but that's about it I think.

  • Kim and TheGoldenPotato like this

#3982 How do I get comments in a steam profile?

Posted by Vanish on 28 July 2017 - 05:26 AM

How to get a comment that is posted in a steam profile

  • LeighHyday and ReighHyday like this

#2838 Send items problem

Posted by Soska on 03 March 2017 - 10:56 AM

Hello. There was such problem: when the bot sends two DIFFERENT trades at the same time, for example where there are two or three of the same case. One trade is accepted, the other gets the status "Items unavailable for trade"
Items are sent by Market name (the classid and instanceid is always the same. they do not have sense). assetid in the offer and the inventory are different.
The task such: to send items that are not currently in other trades of the account.

  • ArlaSokindy and Penneyliz 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

#4355 Already logged on, cannot log on again

Posted by Dr. McKay on 23 September 2017 - 04:36 PM

Sleeping won't work. You need to use setTimeout to delay asynchronously. Delaying synchronously breaks pretty much everything, always.

  • Frohser likes this

#3897 CSGO Float and Phase Market Prices 3rd Party API

Posted by Demby on 14 July 2017 - 10:43 AM



Does anyone know of a 3rd party API that can get the market prices and consider it's Float and Phase? Really appreciate answers.. Thanks.

And does anyone know if Steamanalyst can track the prices of items with different Float and Phase ?

  • kit4 likes this

#3621 How to get the traded items ?

Posted by TomYoki on 14 June 2017 - 05:35 PM

    offer.itemsToReceive.forEach(function(item) {
        if (item.appid == "440" &&  item.market_hash_name == "Scrap Metal") {
            console.log("It's a bird! It's a plane! IT'S A SCRAP METAL!");

Something I made you real quick. 

You can do it the same way for itemsToGive


You can also get some of this info out of it:


  • xLeeJYx likes this

#3147 Error: SteamGuardMobile

Posted by Dr. McKay on 15 April 2017 - 08:41 PM

You can't use the same 2FA code twice. That means that effectively you can't login twice within 30 seconds.


That said, you don't have to. SteamUser will give you login cookies you can use with SteamCommunity.

client.on('webSession', function(sessionID, cookies) {

  • TotallyNotABOT likes this

#3112 Card Sets

Posted by Dr. McKay on 08 April 2017 - 05:08 PM

The easiest way to determine which game a community item belongs to is to check its market_hash_name. All cards/emoticons/backgrounds have their market_hash_names prefixed with the game's appid and a hyphen (e.g. "440-SCOUT").

  • TomYoki likes this

#2750 webSession not fire when i call webLogOn() ?

Posted by Dr. McKay on 22 February 2017 - 03:07 PM

I've been investigating this for the past hour and a half or so, and it appears that Valve did indeed break something with client-based web logons last night. The API is giving quite a lot of 403s with the same error message that you get if you use a bad nonce. Therefore, my suspicion is that there's some kind of miscommunication between the CM (the server which most likely generates the nonce and issues it to you), and whichever server consumes those nonces to turn them into cookies. I've tried adding some delays just in case the communication between those servers is slow, but that doesn't appear to have helped anything.


Re-logging your client seems to solve the problem, at least temporarily. You may want to try doing that if you don't get a web session within a reasonable amount of time after requesting one.


I've alerted Valve, but there's no telling if or when they'll take action.

  • mrxbell likes this

#2615 how to get assetid after accept offer

Posted by Dr. McKay on 31 January 2017 - 08:37 AM


  • pipskas likes this

#2256 How to only accept CSGO keys in 'newOffer'

Posted by Dr. McKay on 10 December 2016 - 12:16 AM

offer.itemsToReceive contains an array of the items you'd receive if you accepted this offer. For each item in this array, check appid to make sure it's CS:GO and name to make sure it's a key. For example:

var allItemsAreGood = offer.itemsToReceive.every(function(item) { return item.appid == 730 && item.name == "CS:GO Case Key"; });

  • Coyeks likes this

#1875 bind ip to node-steam-user & node-steamcommunity

Posted by Dr. McKay on 11 October 2016 - 12:13 AM

The constructor is new SteamCommunity()

  • mtn likes this

#1788 relogin to steam

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


  • GHOST likes this

#1329 getReceivedItems(Empty) how to recheck ?

Posted by Dr. McKay on 09 July 2016 - 04:13 PM

You need to do it yourself.

  • Gilroy likes this