Installing Steam Workshop Mods
Arma 3 has full Steam Workshop support built into the Mods tab. Browse the Workshop, pick a mod, and install it directly — Spawnly reads the installed list live from the server's own files, so what you see always matches what's actually on disk.
Your server must be Stopped before you install or remove any Workshop mods. Changes made while the server is running won't take effect — stop it first, make your changes, then start it back up.
You don't need to manage mod "keys" yourself. Spawnly handles the @modid-style folder referencing and key setup automatically whenever you install or uninstall a mod through the Mods tab.
Installing Mods Not on Steam Workshop
Not every Arma 3 mod is on Workshop — some are distributed as standalone downloads. Spawnly's server process automatically scans the server's root folder at every startup for any folder whose name starts with @ (Arma's standard mod-folder convention) and appends it to the launch command for you. That means you can install a non-Workshop mod manually:
- Open the Files tab (File Manager).
- Create a new folder in the server root named exactly
@YourModName— the@prefix is required. - Upload the mod's files into that folder, preserving its internal structure (typically an
addonssubfolder). - Restart the server. It's picked up automatically — no separate registration step needed.
This works alongside Workshop mods; both are combined into the same launch command on startup.
Good to Know: Server Config Files
Arma 3 ships with an auto-generated server.cfg in the server root (hostname, passwords, max players, signature verification) and a profile/Users/server/server.Arma3Profile file that controls view distance — 3000m by default, with a slightly lower 2500m preferred object view distance for performance. Both are plain text and editable via the File Manager if you want to fine-tune them after installing mods that affect terrain or object density.
Next Steps
New to the Workshop browser itself? Read Installing Steam Workshop Mods. Running Arma Reforger too? See Installing Mods on Your Arma Reforger Server. Take a backup before a big mod change with Managing Backups & Restoring Your Server.