---
title: "Setting up Steam Workshop and FastDL for Garry's Mod"
description: "Link a Workshop collection ID, configure sv_downloadurl fast downloads, and compress custom content to slash player loading times."
url: "https://www.gameserverkings.com/knowledge-base/garrys-mod/workshop-and-fastdl/"
category: "Garry's Mod"
category_url: "https://www.gameserverkings.com/knowledge-base/garrys-mod/"
published: "2026-07-02T02:12:11.329Z"
updated: "2026-07-31T23:04:36.792Z"
source_format: "markdown"
site: "GameServerKings"
---

# Setting up Steam Workshop and FastDL for Garry's Mod

GMod's greatest strength is its Steam Workshop. This guide covers pulling Workshop content onto your server via a collection, and setting up fast downloads so players are not stuck waiting forever for addons. Complete [Getting started with your Garry's Mod server](/knowledge-base/garrys-mod/getting-started-with-your-server/) first.

## Steam Workshop Integration

GMod servers load Workshop addons through a **collection**: a single Workshop item that bundles many addons. You point the server at the collection ID and it downloads everything inside.

### Step 1: Create a Workshop Collection

1. Go to `steamcommunity.com/workshop/browse/?appid=4000`.

2. Click **Create Collection**.

3. Add the addons and maps you want, then save.

4. Note the **Collection ID** from the URL (e.g., `?id=12345`).

Keeping all your server's content in one collection makes it easy to manage and lets players subscribe to everything at once.

### Step 2: Set the Collection ID

In the Startup tab, find the **Workshop Collection ID** field (or `WORKSHOPID` variable). Paste the collection ID.

### Step 3: Set a Workshop Auth Key

Workshop downloads require a Steam Web API key:

1. Go to `steamcommunity.com/dev/apikey`.

2. Register for a key (free for any Steam account).

3. In the Startup tab, paste the key into the **Workshop Auth Key** field.

> [!IMPORTANT]
> Without both the collection ID and the auth key, the server cannot download Workshop content.

### Step 4: Restart

The server downloads all addons in the collection to `garrysmod/cache/workshop/` on boot. The first boot with a large collection takes a while.

> [!TIP]
> Players auto-download missing addons when they connect, but the in-game Workshop download is slow. Set up fast downloads (below) to speed this up dramatically.

## Fast Downloads (sv_downloadurl)

This is essential for any GMod server with significant Workshop content.

### The Problem

Without `sv_downloadurl`, players downloading addons from the game server are throttled to roughly 20 KB/s (the Source engine limit). For a 200 MB addon pack, that is an unbearable wait, and many players disconnect before it finishes.

### The Fix

Host your content on a normal HTTP web server and point the game at it:

1. Extract the Workshop GMA files (from `garrysmod/cache/workshop/`) or gather your custom content.

2. Host them on an HTTP server, your own or a CDN.

3. Add to `server.cfg`:

   ```cfg
   sv_downloadurl "https://fastdl.yourdomain.com/garrysmod/"
   sv_allowdownload 1
   ```

4. Mirror the server's `garrysmod/` folder structure on the HTTP host so paths line up.

Players then download missing files from your fast URL at full speed instead of the throttled game server.

### Workshop vs Fast Download

These two systems complement each other:

- **Workshop** (collection + auth key): how the server itself gets the addons, and how players can pre-subscribe
- **Fast download** (`sv_downloadurl`): how players get any content not covered by their Workshop subscriptions, at full speed

A well-configured server uses both: a Workshop collection for the bulk of content, and a fast download URL as the speedy fallback.

## Compressing Fast Download Files

Source supports bzip2-compressed downloads. Compress files to `.bz2` and host both versions. Clients download the smaller compressed file and decompress locally, cutting download time. The `bzip2` command-line tool produces these.

## Common Issues

- **Players cannot download Workshop content**: Confirm both the Workshop Collection ID and the Auth Key are set in the Startup tab. Without both, nothing downloads.
- **Server stuck loading a map**: The map is missing from the collection or cache. Confirm the map is in your Workshop collection and the server finished downloading it.
- **Addons download but extremely slowly**: `sv_downloadurl` is not set. Set up fast downloads.
- **FastDL returns 404**: The folder structure on the HTTP host does not mirror the server's `garrysmod/` paths. Fix the path layout.
- **Collection too large, boot times out**: Very large collections take a long time on first boot. Be patient on the first start, or trim the collection.

## What to Read Next

- [Game Modes](/knowledge-base/garrys-mod/gamemodes/) since most game mode content and maps come through the Workshop
- [Admin Mods](/knowledge-base/garrys-mod/admin-mods/) for managing the players who join
- [Getting started with your Garry's Mod server](/knowledge-base/garrys-mod/getting-started-with-your-server/) for the `server.cfg` settings referenced here

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