Factorio Mod Portal website:
At this time, Factorio does not support the Steam Games workshop system.
Factorio's developers have instead created their own website called the Mod Portal to allow the players to share mods. You can access the Mod Portal from inside the game or directly from your browser outside the game.
Accessing Portal from inside Factorio:
Mods from the Mod Portal website can be accessed from the "Mods" option in the game's Main menu. Click the "install" button, and a list of the mods available on the Mod Portal will appear. Players can browse mods, and then download and install them automatically. You can also disable and enable mods from this menu.
Information on the mods provided within the install window is very brief. If you access the mods from your browser from your browser outside the game, you will have much more detailed information about the mods.
Downloading Mods directly and Manual Installation:
Mods can be downloaded directly from the Mod Portal in the form of .zip files.. To install the mod, you need to copy the zipped file into the mods directory located under the user data directory without unzipping it.
File location for Mods: On our Nodecraft Factorio servers, mods will be placed in the folder
mods in the main directory (root directory)
Here are the file paths for the default installations of Factorio on the following operating systems:
For Mac OS X:
If the mod is installed correctly, start Factorio, and it should show on the "mods" page accessed from the game's main menu. Mods can also be enabled or disabled from this menu.