Upstack
by FlyInEly
Upstack changes the maximum stack size of common items and patches several stacking bugs, on Fabric and NeoForge for 1.21.1.
What it does
Upstack raises the maximum stack size of items such as water buckets, music discs and snowballs, and it can be reconfigured. A config file sets a stack size per item, per item tag or per datapack, and values outside 1 to 99 are clamped into that range. Setting a value to 0 keeps the original size. A value set on an individual item overrides a value set on a tag, and when one item sits in two tags with different values, a datapack value takes precedence. Changes apply after the server restarts.
Upstack also sets use cooldowns on selected items. The default configuration adds short cooldowns to snowballs and throwable potions, and a cooldown of 0 removes it completely. Cooldown changes apply immediately. The mod needs Fabric API on Fabric and Forge Config API Port on NeoForge, and Mod Menu is optional. It is open source under the GNU General Public License v3.0 only and runs on client and server, so both the server and every player must install it for the patches to work correctly.
Key features
Configurable stack sizes
Maximum stack sizes can be set per item, per item tag or through datapacks, with a config file that lists every value.
Bug patches
Patches address a powder snow bucket that deletes remaining items in its stack and a few other stacking exploits.
Item cooldowns
Selected items such as snowballs and throwable potions can receive a use cooldown, set in ticks in the config.
Default balance
The default configuration raises stack sizes for several common items and adds modest cooldowns to match.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 2
Optional 1
How it compares
Bigger Stacks(Unofficial) is a NeoForge-only mod for 1.21.1, client-side only and open source under the GNU General Public License v3.0 only. Stack Size Tweaks covers Fabric and NeoForge for 1.21 – 26.3 and is open source under the MIT License, running on client and server. Stacked is Fabric-only for 1.21.1 – 1.21.8, also client and server, and is open source under the MIT License.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Upstack | Fabric and NeoForge | 1.21.1 | Client and server | 2026-06-05 |
| Bigger Stacks(Unofficial) | NeoForge | 1.21.1 | Client-side only | 2025-11-29 |
| Stack Size Tweaks | Fabric and NeoForge | 1.21 – 26.3 | Client and server | 2026-09-25 |
| Stacked | Fabric | 1.21.1 – 1.21.8 | Client and server | 2025-08-14 |
Questions
Does Upstack need to be installed on the server?
Which dependencies does Upstack require?
Do stack size changes take effect without a restart?
In the catalog
Upstack is one of 4,058 Storage mods on ModsFinder, and one of 2,474 Storage mods for Fabric. 32,366 mods support Minecraft 1.21.1.
Similar mods
What the author says
An open-source mod which makes the max stack size of common items configurable. Patches bugs that occur when some items are made stackable. Disclaimer: This mod is a passion project, so support for any particular version or feature is not guaranteed. Feedback and feature requests (without expectation) are welcome.
Official listing
- Modrinth page
- modrinth.com/mod/upstack
- Owner
- FlyInEly
- Published
- 2026-03-29
- Updated on Modrinth
- 2026-06-05
- Facts verified
- 2026-10-15