Yet another larger backpack mod. Many of them are made to be compatible with specific mods. This one is simple and standalone… except the 90 slot is recommended to have some kind of HUD mod that lowers the toolbelt. More details below.
Bigger Backpack xml only (works server side). Main one is 90 slots, which also includes extra crafting slot, larger output, and expanded vehicle storage. (Requires a HUD that lowers the toolbelt). Other option is 60 slot, which works just like vanilla but with extra slots (does not require HUD modification).
Download 60 Slot Version (Basically vanilla with a larger inventory.)
Download 90 Slot Version (With the 90 Slot option, it is recommended to use a modified HUD in which the toolbelt is lowered. One option is Riles HUDPlus.)
The forum topic of the mod is here.