# How to add mods to an Arma 3 server > Add mods like CBA, ACE, RHS and CUP to an Arma 3 server, with their keys, the -mod and -serverMod lists, lowercase names and a preset for your players. By the Wilderack Crew. Last reviewed 2026-11-14. First published 2026-11-13. Topic: Mods and plugins. _Wilderack is not affiliated with Bohemia Interactive. Arma 3's server license is for personal use, so Arma 3 servers open on Wilderack only once Bohemia gives us its written OK._ _Arma 3 is a trademark of Bohemia Interactive a.s. Wilderack is not affiliated with or endorsed by Bohemia Interactive a.s._ Arma 3 mods add weapons, vehicles, maps and whole new systems, like ACE's medical rules. A server runs them from its `mods` folder, checks players' mods against the keys in its `keys` folder, and every player loads the same set in the Arma 3 Launcher. > [!NOTE] > Arma 3 servers can't be ordered on Wilderack yet. We open Arma 3 once Bohemia Interactive gives us its OK. This guide shows how mods will work then, and the steps are the same on any Arma 3 server. ## How Arma 3 mods work - Each mod is a folder whose name starts with `@`, like `@cba_a3`. Inside are `addons` with `.pbo` files, and usually a `keys` folder with a `.bikey` file. - The server loads the mods named on its start line. `-mod` is for mods players need too. `-serverMod` is for mods only the server runs. - Many mods need others. ACE, for one, needs CBA. Load the required mod first. - Players load the same mods in the Launcher, at the same versions. ## Get the mod files The server can't download Workshop mods itself: Workshop downloads for Arma 3 need a Steam account that owns the game, and we never use a Wilderack or customer login for that. So you upload the mods you play with: 1. Subscribe to the mods on the Steam Workshop, and let the Launcher download them. 2. Find each mod's folder on your PC. The Launcher lists Workshop mods in your Arma 3 folder, under `!Workshop`. In Steam, right-click Arma 3, choose **Manage**, then **Browse local files**. 3. Copy the folders you need to one place, and rename each folder to lowercase, like `@ace`. Your group's own mods, or mods from outside the Workshop, go up the same way. ## Upload and turn them on 1. Upload each mod folder to `mods` in **Files**, or over SFTP for big mods. 2. Copy each mod's `.bikey` file into the server's `keys` folder. 3. Open **Settings**, then the advanced settings. 4. In the **Mods** setting, list the folders with semicolons, required mods first, like `mods/@cba_a3;mods/@ace`. 5. Put server-only mods in **Server-only mods** the same way. 6. Restart. The console shows which mods the server loaded. If one is missing, missions that need it won't start, and the console names the missing addon. ## Lowercase names on Linux Wilderack runs the Arma 3 server for Linux. Linux treats `@ACE` and `@ace` as different names, and the server looks files up in lowercase. Keep every mod folder lowercase. If a mod still fails to load, rename the files inside it to lowercase too. A tool on your PC can rename a whole folder at once. ## Signature checks With **Players may only load signed mods** on, the server checks each player's mods against the keys in `keys`. A player with a mod the server has no key for gets kicked. That stops changed or cheat mods, so keep it on for public servers. If a player is kicked over signatures, check that the mod's key is in `keys` and that they run the same version as the server. ## Share the mod list with players 1. In the Launcher's **Mods** tab, load exactly the server's mods. 2. Export them as a preset. You get a small file listing every mod with its Workshop link. 3. Share it on your Discord. Players import it and subscribe to anything they lack. The Launcher's **Servers** tab also shows which mods your server runs. ## Updating mods When a mod updates on the Workshop, players get the new version and the server keeps the old one until you upload it. Players on the newer version may be kicked for signatures. Upload the new folder and key, then restart. Take a backup in **Backups** first. ## Mods and memory Big mod sets such as RHS and CUP add many gigabytes of data the server loads into memory. If you run them, see [performance](https://wilderack.com/wiki/arma-3/performance/) for the plan they need. ## Questions and answers ### How do I add Workshop mods to an Arma 3 server? Subscribe to the mods on your own PC, then upload each mod's folder, like @cba_a3, to the server's mods folder and its .bikey file to keys. List the folders under Mods in Settings and restart. Workshop downloads need a Steam login that owns Arma 3, so the server doesn't fetch them itself. ### What is the difference between -mod and -serverMod? Mods in -mod must be loaded by every player as well as the server. Mods in -serverMod run only on the server, for things like admin tools or database add-ons, and players don't need them. ### Why do Arma 3 mods need lowercase names on a Linux server? Linux file names are case sensitive, and the Arma 3 server for Linux looks files up in lowercase. A folder called @CBA_A3 may not be found. Rename mod folders, and the files in them if the mod needs it, to lowercase. ### What are .bikey files for? Each signed mod comes with a key. With signature checks on, the server only lets in players whose mods are signed by a key in its keys folder, which stops people joining with changed or extra mods. ## Sources - [Arma 3: Dedicated Server](https://community.bistudio.com/wiki/Arma_3:_Dedicated_Server), Bohemia Interactive Community Wiki - [Arma 3: Startup Parameters](https://community.bistudio.com/wiki/Arma_3:_Startup_Parameters), Bohemia Interactive Community Wiki - [Arma 3: Server Config File](https://community.bistudio.com/wiki/Arma_3:_Server_Config_File), Bohemia Interactive Community Wiki - [Arma 3 Workshop](https://steamcommunity.com/app/107410/workshop/), Steam --- Canonical page: https://wilderack.com/wiki/arma-3/mods/ How we write and check our guides: https://wilderack.com/company/editorial-policy/ Corrections: support@wilderack.com