Missing Mods Checker

Missing Mods Checker is a simple utility mod for modpack devs that hooks into the pre-loading process for Forge & Fabric to check if any dependencies are missing before the game loads. If any are found to be missing, a window will pop up prompting the user to download them before restarting.
 

This utility mod can serve multiple purposes:

• Prevent important mods from being accidentally or deliberately removed
• Enforce exact versions of mods, to prevent accidental end-user updates
• Prompt to download mods that are only available on certain platforms
• Allow users to download optional mods the first time the game starts up

Whatever the reason mods are found to be missing, the mod will open up a simple Java Swing window with a list of all missing mods. The user can click “download,” which will open the link specified in the config file in their browser. To make things easier, there is a button that opens the mods folder directly.

You can configure the mod by editing missing_mods_checker.json in your modpack’s config folder, and adding in entries for each mod. The dependency scanning supports regex for filenames, so you can specify exact versions, or a regex match for anything you would like.