Why Garry's Mod works differently
Most Workshop-enabled games on Spawnly give you a searchable Workshop browser for installing individual mods one at a time. Garry's Mod doesn't work that way — instead, you point your server at an entire Steam Workshop Collection, and the server downloads and keeps everything in that Collection synced automatically.
Setting up a Workshop Collection
- Get a Steam Web API key from
steamcommunity.com/dev/apikey. This key is tied to your own Steam account, not to Spawnly — treat it like a password. - On Steam, create or find the Workshop Collection containing every addon you want your server to run. The Collection ID is the numeric value in that Collection's Workshop URL.
- Open your server's Mods tab and enter both the API key and the Collection ID.
- Restart the server. Garry's Mod downloads every item currently in the Collection and mounts it for players.
Updating your mod list
Because the Collection is the single source of truth, you manage your server's mod list by adding or removing items from the Collection on Steam — not by adding items one at a time in Spawnly's dashboard. After changing the Collection, restart the server to re-sync.
Keep a single curated Collection for your server rather than juggling several — swapping Collection IDs on the Mods tab replaces the entire mod set on the next restart.
Good to know
Your API key and Collection ID are written into a file called spawnly-args.json in your server's root folder (as the -authkey and +host_workshop_collection launch parameters), visible through the File Manager if you want to double-check what's configured. This file is actually a general Spawnly mechanism that merges any custom launch parameter into the server's start command — the Mods tab is just the friendly way to edit it for Garry's Mod.
Next steps
Read Installing Steam Workshop Mods for how the Workshop flow typically works on other games, and set up Managing Backups & Restoring Your Server before syncing a large Collection.