Herzium
by zymery_dria
Herzium changes how Minecraft handles hotbar slot switches and item use timing on the client, so that quick hotbar presses and item use land on the frame the player pressed them.
What it does
Herzium is a client-side Fabric mod that alters hotbar input so a slot switch takes effect on the next frame instead of waiting for the next game update, which can bring the item into the hand up to about 50 ms sooner on high-refresh monitors. Weapons keep their normal animation unless a single switch would otherwise put the hand up more than once.
Herzium depends on Fabric API and can use Mod Menu for its settings screen. Pressing two hotbar keys together can be resolved in three ways, chosen in the Order tab: the last key pressed wins, the highest slot wins as in vanilla, or the lowest slot wins. The Order tab settings take effect after a restart. The mod is released under the MIT License and is open source, with its source code, issue tracker and wiki publicly available.
Key features
Next-frame hotbar switching
A slot switch is drawn on the next frame, so the held item changes without waiting for the following game update.
Configurable simultaneous key order
When two hotbar keys are pressed together, the Order tab decides whether the last key, the highest slot or the lowest slot is selected.
Same-tick item use
Quick sequences such as placing obsidian and using a crystal, or detonating a rail TNT minecart, resolve inside one tick in the order they were pressed.
Offhand totem sync
A totem swapped into the offhand takes effect in the same tick, and a hold guard keeps an item from being placed again with the old item.
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 1
Optional 1
How it compares
Hotbar Layout Editor is a Fabric mod for 1.21.4 – 26.1.2 under the MIT License, but it is not open source and is also client-side only. Scroll2Key is a Fabric mod for 1.20.1 – 26.2 released under CC0 1.0 Universal, which is open source, and it is client-side only. Hotbar Quickswap is also client-side only and is open source under CC0 1.0 Universal, but it covers only 1.21.10 – 1.21.11.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Herzium | Fabric | 1.21.10 – 26.3 | Client-side only | 2026-10-12 |
| Hotbar Layout Editor | Fabric | 1.21.4 – 26.1.2 | Client-side only | 2026-05-22 |
| Scroll2Key | Fabric | 1.20.1 – 26.2 | Client-side only | 2026-07-12 |
| Hotbar Quickswap | Fabric | 1.21.10 – 1.21.11 | Client-side only | 2025-12-24 |
Questions
Does Herzium need Fabric API?
Does Herzium have to be installed on the server?
Which game versions does Herzium support?
Where is the mod's option for simultaneous hotbar keys?
In the catalog
Herzium is one of 36,990 Utility mods on ModsFinder, and one of 25,772 Utility mods for Fabric. 8,071 mods support Minecraft 26.3.
More from zymery_dria
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What the author says
Herzium Your hotbar switches on the very next frame — and you choose which slot wins. Minecraft waits for its next game update to show a hotbar switch. Herzium draws it on the next frame: up to about 50 ms sooner on a high-refresh monitor. Every item appears in hand right away; weapons keep their normal animation…
Official listing
- Modrinth page
- modrinth.com/mod/herzium
- Owner
- zymery_dria
- Published
- 2026-08-03
- Updated on Modrinth
- 2026-10-12
- Facts verified
- 2026-10-15