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Pack Installation using packwiz-installer

packwiz-installer is a Java-based installer that allows for automatic installation and updates of packwiz packs! It can be used with MultiMC as a prelaunch task, or on servers as part of your start script, and supports side-only mods as well as optional mods with a fancy GUI.

To distribute a packwiz modpack, you'll first want to set up a web hosting service (such as Netlify, Github Pages, GitLab Pages) so that your pack files are accessible from a HTTP/HTTPS link. For testing, you can use the packwiz serve command to run a local HTTP server, that serves your pack at http://localhost:8080/pack.toml - it'll refresh the index whenever it's queried so you don't need to refresh it manually!

Creating a MultiMC instance for your modpack

To distribute the modpack as a MultiMC instance:

  1. Create a barebones MultiMC instance, with the modloader and Minecraft version you want (memory allocation overrides are also a good idea)
  2. Download packwiz-installer-bootstrap from and place it in the instance Minecraft folder


This is the same folder as options.txt - MultiMC will call it .minecraft or minecraft depending on your system.

  1. Go to Edit Instance -> Settings -> Custom commands, then check the Custom Commands box and paste the following command into the pre-launch command field:
    • "$INST_JAVA" -jar packwiz-installer-bootstrap.jar https://[your-server]/pack.toml (where https://[your-server]/pack.toml is the HTTP URL your pack.toml file is hosted at)
  2. Use the Export Instance function to export your pack as a .zip file (which can be distributed similarly to your pack via a web hosting service)

To install your pack, users just need to add it with Add instance -> Import from zip - then packwiz-installer does the rest, keeping it up to date every time the game is launched!

Using a modpack with a server

You can use packwiz-installer to download non-client mods (side either both or server), for example:

java -jar packwiz-installer-bootstrap.jar -g -s server https://[your-server]/pack.toml
  • -g flag to disable the GUI
  • -s server to download only server-side mods.

itzg's docker-minecraft-server has built in support for packwiz. You can pass the PACKWIZ_URL environment variable pointing to your pack's TOML file, and the container will bootstrap packwiz-installer and install/update the provided pack. See the documentation for more information.