PackUpdate is an automatic modpack updater built for MultiMC.
This modpack updater only requires the author of the modpack to create a csv file which contains the mod names, versions and download links. It then automatically gets the online version of the file hosted by the author, compares it to a local version and downloads all mods that changed in the meantime (or every mod if it is the first launch of the modpack). This way a modpack author only has to redistribute a very small MultiMC instance that holds the updater with the link to the online file.