How to Use a Steam Workshop Collection on a Dedicated Server

A few games can load a whole Steam Workshop collection on a server with one setting: Garry's Mod and Counter-Strike 2 both take +host_workshop_collection <id> on the command line. Most others, like Project Zomboid, Conan Exiles, Space Engineers and Killing Floor 2, want a list of individual Workshop item IDs instead. For those, you expand the collection into its item IDs (Steam's public Web API does it in one request), paste them into the game's mod setting, and the server downloads them on start. Players then subscribe to the same collection so their mods match.

Find the collection ID

Open the collection in a browser. The ID is the number at the end of the URL:

https://steamcommunity.com/sharedfiles/filedetails/?id=1234567890

Here the collection ID is 1234567890. Item IDs look the same, so make sure the page says "Collection" at the top, not a single item.

Make the collection public or unlisted. A private or friends only collection cannot be read by the server.

Games that load collections directly

Garry's Mod

Add the collection to the launch options:

+host_workshop_collection 1234567890

The server downloads every addon in the collection on start and tells joining players to download them too. If the collection does not download, older setups also needed a Steam Web API key passed with -authkey <key>, which you can get from Steam's developer key page. Large collections slow down joining, so trim anything players do not need. Our guide on adding Workshop addons to a Garry's Mod server covers server side vs client side content.

Counter-Strike 2

+host_workshop_collection 1234567890

That makes the collection's maps available on the server, and +host_workshop_map <id> starts on a specific one. For map changes and the full setup, see how to play CS2 Workshop maps on a server.

Turning a collection into item IDs

For everything else, you need the list of IDs inside the collection. Steam's public Web API has a method for this, ISteamRemoteStorage/GetCollectionDetails, which needs no API key:

curl -s -d "collectioncount=1&publishedfileids[0]=1234567890" \
  https://api.steampowered.com/ISteamRemoteStorage/GetCollectionDetails/v1/ \
  | jq -r '.response.collectiondetails[0].children[].publishedfileid' \
  | paste -sd ';'

That prints the item IDs joined with semicolons, ready to paste into Project Zomboid. Swap ';' for ',' for games that want commas. On Windows, you can run the same request in PowerShell:

$r = Invoke-RestMethod -Method Post -Uri "https://api.steampowered.com/ISteamRemoteStorage/GetCollectionDetails/v1/" -Body "collectioncount=1&publishedfileids[0]=1234567890"
($r.response.collectiondetails[0].children.publishedfileid) -join ';'

Collections can contain other collections. If the output includes an ID that is itself a collection, run the request again for that one.

Where the IDs go, game by game

Downloading items by hand

If a game does not download Workshop items itself, use SteamCMD:

steamcmd +login anonymous +workshop_download_item 108600 <itemid> +quit

The first number is the game's app ID (the game, not the server), then the item ID (108600 is Project Zomboid). Items land in steamapps/workshop/content/<appid>/<itemid>. Some games need an account that owns the game for Workshop downloads, DayZ and Arma 3 among them. See anonymous login vs owned games.

Order matters

The order of items in a collection is not always the order mods load. In games where load order matters, such as Project Zomboid maps or frameworks that other mods depend on, set the order in the server config yourself. Put libraries and frameworks first, content mods after, and map mods in the order their authors recommend.

Keep server and players in sync

1. Share the collection link with players and ask them to subscribe to the whole thing.
2. When you add or remove items, update both the collection and the server config at the same time.
3. Restart the server after Workshop updates so it pulls the new versions. Mismatched versions are the top cause of "mod mismatch" kicks. See game server version mismatch.
4. Keep a backup before big mod changes, because removing a mod that added items or buildings can damage a world.

Collections on a hosted server

On a GamezServers server some games have Workshop fields in the control panel: Project Zomboid has Workshop items and mod IDs, and ARK: Survival Ascended has a mod ID field. For other games, edit the config or launch options through the file manager or SFTP. See the modded hosting page for Project Zomboid, or browse all our games.

FAQ

Can a dedicated server use a Steam Workshop collection?

Garry's Mod and Counter-Strike 2 can load one directly with host_workshop_collection. Most other games need the item IDs from the collection listed in their config.

How do I get all the item IDs from a collection?

Call Steam's GetCollectionDetails Web API with the collection ID. It returns every item ID in the collection, no API key needed.

Why does my server not download the collection?

The collection may be private or friends only, the ID may be an item rather than a collection, or the game may not support collections and needs item IDs.

Do players need to subscribe to the collection?

In most games, yes, or the game downloads the mods when they join. Either way, their versions must match the server's.