
Build undo
Build Undo adds a safe undo and redo system for accidental block placements in Minecraft.
Screenshots

About this Mod
Build Undo is a lightweight quality-of-life Fabric mod for builders who sometimes place a block in the wrong spot and want a quick, fair way to fix it.
The mod tracks your own successful block placements and lets you undo or redo them with keybinds. It is designed to feel like a small building helper, not a cheat tool or WorldEdit replacement.
Features
Undo your own recently placed blocks
Redo blocks you just undid
Per-player placement history
Configurable history size
Configurable undo/redo distance
Optional item return in Survival
Optional sound and particle effects
In-game settings screen
Server-side safety checks
No undo for blocks changed after placement
No undo for naturally generated blocks or other players’ blocks
Default Keybinds
Z: Undo last placed block
Y: Redo last undone block
U: Open Build Undo settings
Commands
/buildundo undo
/buildundo redo
/buildundo config show
/buildundo config history <1-1000>
/buildundo config distance <0-256>
/buildundo config returnItems <true|false>
/buildundo config effects <true|false>
Use distance 0 for unlimited range.
Compatibility
Minecraft (show versions)
Fabric Loader
Fabric API required
Available Versions
How to Install Build undo on Your Server
Order Server
Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.11).
Install Mod
Open the mod browser in the dashboard and search for "Build undo". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
1.21.11
Server-side
✓ RequiredRecommended RAM
4 GB(min. 3 GB)Frequently Asked Questions
Build undo server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (1.21.11). You can switch loaders with one click in the panel.
Is Build undo compatible with fabric?
Build undo officially supports fabric for Minecraft 1.21.11. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with Build undo – how to optimize performance?
Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Build undo consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
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Rent Modded Server
Install Build undo with just one click on your server.