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Server Setup

Get ready to launch your very own Just Cause 4 Multiplayer server! 🚀 In just a few simple steps, you'll have your server up and running, ready to welcome players from around the world.

Follow this guide step-by-step, and you'll be hosting chaos in no time!

Step 1: Download the Server​

First things first - you'll need to download the server files for your platform. Head over to the Servers page and grab the latest build that matches your system.

Important: Make sure the server version matches your client version - players can only connect if their client version matches the server version exactly!

Linux Users

If you're running Linux, make sure you're on Ubuntu 24.04 or above. Check out the Linux Compatibility section for more details!

Step 2: Generate Your Config File​

Once you've downloaded and extracted the server files, run the server for the first time. This will automatically create a default configuration file at cfg/config.json with all the necessary settings!

Simply start your server executable - it will generate the config file and then exit (or you can stop it manually). Don't worry about any errors you might see during this first run - we'll configure everything next!

Step 3: Customize Your Server Name and Description​

Open up cfg/config.json in your favorite text editor. You'll see a default configuration file with all the necessary fields.

Update these two fields to make your server unique:

  • name - Choose a catchy name that will appear in the server browser!
  • description - Write a fun description that tells players what your server is all about!
{
    "name": "My Awesome JC4MP Server",
    "description": "Come join us for epic multiplayer chaos and destruction!",
    // ... rest of config
}

Step 4: Get Your JC4MP Server Key​

To make your server appear on the official JC4MP server list, you'll need a server key!

  1. Visit the JC4MP Server Dashboard
  2. Log in with your Steam account
  3. Generate a new server key (it will look like JC4MP_pBJVVEZXi3V1e3FDTC039hnc2QYAXloP)
  4. Copy the key and paste it into the key field in your config.json
Keep Your Key Safe

Never share your server key with anyone! This key is unique to your server and should be kept private. If you need multiple servers, generate a separate key for each one.

Step 5: Get Your Steam Web API Key​

Your server needs a Steam Web API key to authenticate players through Steam. Don't worry - this is free and easy to get!

  1. Visit Steam's Web API Key page
  2. Log in with your Steam account
  3. Enter a domain name (you can use any valid domain, such as example.com - this is just for identification)
  4. Click "Register" and copy your API key
  5. Paste it into the steam_web_api_key field in your config.json
One Key, Many Servers

You can use the same Steam Web API key for all your servers - no need to generate a new one for each server!

Make your server stand out in the server browser with custom images!

Server Icon​

  • Size: 512x512 pixels (square)
  • Format: PNG, JPG, or WEBP
  • Max Size: 1MB
  • Hosting: Use Imgur, Steam, Gravatar, ImageKit, or Cloudinary

Add your icon URL to the icon_url field:

{
    "icon_url": "https://example.com/my-server-icon.png",
    // ... rest of config
}

Server Banner​

  • Size: 1280x720 maximum (766x192 recommended, landscape)
  • Format: PNG, JPG, or WEBP
  • Max Size: 2MB
  • Hosting: Use Imgur, Steam, Gravatar, ImageKit, or Cloudinary

Add your banner URL to the banner_url field:

{
    "banner_url": "https://example.com/my-server-banner.png",
    // ... rest of config
}
Image Guidelines

Using inappropriate or offensive images will result in your server being blocked from the server list. Keep it clean and fun!

Step 7: Configure Your Firewall​

Before starting your server, make sure your firewall allows the necessary ports through!

By default, your server uses port 7777 for player connections. The server also opens a HTTP server on port 7778 (port + 1) for server information and mod distribution.

Make sure both ports are open:

  • Port 7777 (or whatever port you set in the config)
  • Port 7778 (or port + 1)

If you're using a different port, adjust accordingly - always allow both your main port and port+1!

Hosting at Home

If you're hosting your server from home, be aware that your public IP address will be visible to anyone who connects to your server or views it on the server list. This can expose your location and make your home network a target. Consider using a cloud hosting provider or a VPN if privacy is a concern.

Step 8: Start Your Server!​

Everything is configured? Excellent! It's time to launch your server and watch the magic happen! 🎉

Start your server executable and you should see it initialize. Once it's running:

  1. Your server will automatically appear on the JC4MP server list (if you set announce to true and have a valid key)
  2. Players can now find and connect to your server!
  3. You can connect yourself using the JC4MP launcher
Direct IP Connection

You can connect directly to a server by typing the IP address (and port if not using the default) at the top of the JC4MP launcher and pressing Enter. This is useful if the server isn't showing up in the server list or if you want to connect quickly.

If you're hosting locally at home and want to connect from the same machine, you can use localhost or your local IP address (use ipconfig on Windows or ifconfig on Linux/Mac to find your local IP).

What's Next?​

Congratulations! Your server is now running!

Want to customize it further? Check out the Server Configuration guide for all the advanced options available, including:

  • Setting up resources and scripts
  • Configuring access control lists (ACL)
  • Managing mods
  • Setting up DLC requirements
  • And much more!

Ready to add some custom scripts? Head over to the Adding Scripts guide to start building amazing features for your server!

Need help writing scripts? Check out our Chat with Rico page - an AI assistant that can help you learn how to make scripts or even write scripts for your JC4MP server!

Having issues with your server? Check out the Troubleshooting guide for common problems and solutions.

Happy hosting!