Viper Anti-Dupe

Viper Anti-Dupe is a high-performance, Server-Side ONLY configurable anti-duplication mod for Minecraft 1.21-1.21.11, 26.1-26.1.2, and 26.2. Blocks 25+ known dupe methods with zero client mods required. Fully configurable per-method choose what to block and what to allow.

Supported Versions

Purpose & Function

The core mission of this project is to give server administrators total control over duplication prevention on their server.

• Block Every Known Method: Covers book dupe, shulker box nesting, rail/piston/carpet dupes, entity cloning, trident dupes, TNT dupes, beehive dupes, tripwire dupes, string dupes, lectern dupes, gravity block dupes, NBT list dupes, item frame dupes, container desync, death dupes, chunk rollback, portal dupes, bundle dupes, crafter dupes, and more.
• Per-Method Config: Each dupe method is individually togglable no more all-or-nothing protection.
• Audit Logging: Built-in audit log tracks every blocked attempt with timestamps, player names, and dupe type.
• Known Dupable Items: Configurable list of known-dupable items with command management.
• Hot Reload: Change config on the fly no server restart needed.

Dupe Methods Blocked

Enhance your server setup! Check out my other server-side mods over at : Fabric Server Essentials

In-Game Commands

All commands use the /viperantidupe command tree. Requires operator level 2+.

Configuration

Edit config/viper-anti-dupe.json after first launch:

{
  "modEnabled": true,
  "loggingEnabled": true,
  "logFilePath": "logs/viper-anti-dupe-audit.log",
  "maximumItemNbtBytes": 32768,
  "maximumContainerNestingDepth": 3,
  "cancelSuspiciousTransactions": true,
  "knownDupableItems": {
    "minecraft:barrier": true,
    "minecraft:structure_void": true
  },
  "bookDupe": false,
  "shulkerBoxDupe": false,
  "railDupe": false,
  "carpetDupe": false,
  "horseQuickMoveDupe": false,
  "stackSplitDupe": false,
  "hopperDupe": false,
  "pistonDupe": false,
  "entityDimensionDupe": false,
  "tridentDupe": false,
  "beeDupe": false,
  "tripwireDupe": false,
  "stringDupe": false,
  "lecternDupe": false,
  "tripwireHookDupe": false,
  "gravityBlockDupe": false,
  "nbtListDupe": false,
  "itemFrameDupe": false,
  "updateSuppressionDupe": false,
  "containerDesyncDupe": false,
  "deathDupe": false,
  "chunkRollbackDupe": false,
  "portalDupe": false,
  "bundleDupe": false,
  "crafterDupe": false
}

Config semantics: false = BLOCKED (the dupe method is prevented), true = ALLOWED (the dupe method is permitted). This is by design a false-positive safe default blocks everything until you explicitly allow methods you trust. Setting a method to true does not enable any exploit it simply removes the mod's protection against it.

Hot-reload config in-game: /viperantidupe reload

Installation

1. Drop the JAR for your Minecraft version into your server's mods/ folder
2. Install Fabric Loader 0.19.3+ (all versions)
3. Install Fabric API (required for all versions)
4. Start the server config auto-creates at config/viper-anti-dupe.json
5. Review and customize the config to your needs
6. Run /viperantidupe reload or restart the server

Built for administrators who demand robust duplication protection with zero client overhead. Every dupe method is individually configurable block what matters, allow what doesn't.