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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

#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

#3580 Logging in anonymously and relogging with an account

Posted by Dr. McKay on 11 June 2017 - 09:09 PM

No, bot voting is not something I will support.

  • lad likes this

#3435 "Steam Guard App Code" when logging in frequently

Posted by DevDuck on 23 May 2017 - 01:11 AM

Does it appear as online/in-game on its direct profile?

Yes. Moreover in GetPlayerSummaries:


"personastate": 1,
"gameid": "730"

  • DevDuck likes this

#3342 v2.7.3

Posted by System on 16 May 2017 - 10:14 PM

  • Added id property to objects pushed to itemsToGive and itemsToReceive when building a trade offer (PR #225)
  • Made the TradeOffer class exportable for use with Bluebird (PR #227)
    • This still isn't officially supported and may break in the future if you rely on it
  • Updated getExchangeDetails to use new WebAPI method which has greater reliability

View on GitHub
  • SunriseM likes this

#3263 Shared secret and Identity secret

Posted by SunriseM on 05 May 2017 - 09:12 AM

If you set a password, it will be encrypted so you will have to disable it first

  • Enemtia likes this

#3199 get assetIDs by calling getInventoryContents?

Posted by SunriseM on 26 April 2017 - 12:22 PM

You should use a loop (for, foreach, while, etc) to iterate all the inventory callback, you can create an array called items, and in each iteration you push a object like this one:

var item = {
  "assetid": inventory[i].id,
  "name": inventory[i].market_hash_name

if you need to make an asynchronous operation with that info and know when all iterations are finished, you can use async module. 

  • TomYoki likes this

#3157 How long session Expired after logOn ?

Posted by Krank on 18 April 2017 - 08:35 PM

not sure how long it takes for the session to expire, but what I do is just have an event to check if the session expired. If it does, then relog. Or you can also just re log at an interval, say every hour.

  • mrxbell 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

#2330 startConfirmationChecker not starting

Posted by sianbg2 on 16 December 2016 - 04:32 PM

can i debug something more? or change code to get all offers, and confirm 1 by 1? shoud work?

edit: i remember change timezone of vps, maybe this?
  • sianbg2 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

#2109 Custom Storage Engine

Posted by Dr. McKay on 09 November 2016 - 05:38 PM

If that works it's a fluke. You should pass an Error to the callback, like this:

callback(new Error("File not found"));

  • jazz likes this

#1935 Decline Trade Hold

Posted by TextDynasty on 22 October 2016 - 03:14 AM

offer.getUserDetails(function(err, me, them) {
	if (err) {
		throw err;
	if (them.escrowDays > 0) {

One more question how to response to friends message and invite?

  • TextDynasty likes this

#1905 Deleting from poll data

Posted by Dr. McKay on 14 October 2016 - 07:08 PM

It's not really recommended to manipulate poll data. TradeOfferManager's job is to emit newOffer once per incoming offer. Errors can be frustrating but it's your responsibility to make sure that they're dealt with properly.


You could use offerList to check for offers that should have already been accepted (probably want to keep a list of offers you've attempted to accept and the timestamp so you don't try to accept an offer too frequently).

  • Santa likes this

#1788 relogin to steam

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


  • GHOST likes this

#1575 Cannot read property 'escrowDays' of undefined

Posted by Dr. McKay on 12 August 2016 - 01:21 PM

No, that's the actual solution. Errors are a fact of life (especially when you're working with Steam). You need to handle them, or else you'll crash.

  • KiTa likes this

#1482 checking if sent offer has been accepted

Posted by Dr. McKay on 23 July 2016 - 03:36 PM

Please read the documentation. You need to call setCookies and wait for the callback before you try to do anything else, and that is invalid input for getOffer.

  • N4d!r likes this

#1420 Trade offer expire time

Posted by Dr. McKay on 13 July 2016 - 01:29 PM

There might be some confusion here. The expires property is Steam's expiration date, which is always 14 days from creation time and can't be changed. cancelTime works independently of it.

  • RavenX86 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