Which Minecraft versions are supported?

DupeWatch runs on Paper and Folia for Minecraft 1.21.5 and newer, built against the latest Paper 26.x API. One jar covers everything from the Java 21 floor to the Java 25 ceiling, with no NMS and no version-specific builds to juggle.

Will it lag my server?

Not in any way you'll feel. DupeWatch was built for busy servers, so it leans on multi-layer caching, bloom filters, a dirty-flag scanner and async work to cut roughly 80% of the CPU a naive scanner would burn. The heavy lifting never touches the main thread.

How do I update DupeWatch?

Usually you don't have to do anything. Because the plugin runs through the Lukittu loader, new versions are delivered automatically the next time your server starts. Your loader.yml and license stay exactly as they are.

SQLite or MySQL, which should I pick?

SQLite is the zero-setup default and is perfect for most servers. Go with MySQL if you run a network and want shared storage across servers, just set mysql.enabled to true. Upgrading is automatic: any old file data is migrated for you and the originals are kept safe.

Will normal stacked items cause false positives?

Rules are based on a threshold and a time window, so everyday stacking will not trip them once tuned. Start with high thresholds, let the dirty-flag scanner do its thing, and give trusted or creative players the dupewatch.bypass permission. Items handed back from quarantine are re-minted as fresh, legitimate items.

Does it work with CoreProtect and Vault?

Yes, both are optional soft dependencies. With CoreProtect, cases automatically pull in forensic context like block, container, chat and command history. With Vault, Money Watch keeps an eye on balance anomalies. Neither is required for core dupe detection.

Documentation·v1.3.5 · Paper / Folia 1.21.5+

DupeWatch
Wiki

Everything you need to install, activate and run the most advanced anti-dupe plugin for Minecraft. From your very first watch rule to tracing exactly how a dupe spread across your server, it is all here. Clean setup, powerful detection, no guesswork.

Get Started

0%+

CPU reduction

vs. naive scanning

<0.00ms

Event handling

off thread, off your TPS

GUI screens

no commands required

0.00.5+

Paper / Folia

single artifact

Introduction

What is DupeWatch?

DupeWatch spots duplicated items on your server using advanced fingerprinting, opens investigation cases, and gives your staff a full point and click workflow to review, resolve and act. Optional Discord alerts keep your team in the loop.

Smart scanning

It scans inventories, ender chests and nested containers using semantic item fingerprints.

Growth detection

It spots items multiplying over time (5, 10, 20, 40) across scan cycles, not just raw counts.

Case management

Create, annotate, export, confiscate and resolve. A full investigation lifecycle in one place.

15-screen GUI

Run everything with clicks. Commands are there too, for power users and automation.

Discord alerts

High signal webhooks for new cases and confiscations, without the spam.

Built for scale

Caching, bloom filters and async work keep big servers smooth.

The detection pipeline

Scan

Fingerprint

Detect growth

Open case

Gather forensics

Act

About 5 minutes

Quick Start

The quickest path from download to catching your first dupe. Each step links to a deeper section below.

Install the loader

Drop the DupeWatch loader jar into plugins/ and start the server once. It writes a loader.yml file.

Add your license

Paste your key into loader.yml, then restart so the loader can verify it. See License.

Make your first rule

Hold the item you want to watch, open /dw, go to Watchlist and click Add From Hand. See Rules.

Try it out

Run /dw scan on a player, then open the Cases screen to see what turned up.

/dw scan <player>

copy it, then open the Cases GUI

Pro tip

Start with high thresholds (100 or more) and short time windows while you are testing, then tighten them once you get a feel for how your economy behaves. Every rule is editable live from the GUI.

Setup

Installation

DupeWatch ships as a single drop-in jar. Here is what it needs and where its files live.

Requirements

Server software

Paper or Folia, Minecraft 1.21.5+. Folia is fully supported.

Java runtime

Java 21+ at runtime. The jar loads all the way up to the Java 25 ceiling.

Storage

SQLite out of the box. MySQL is there if you run a network.

Soft deps

CoreProtect and Vault unlock forensics and Money Watch. Both optional.

Steps

1Download the latest DupeWatch loader jar from your purchase.
2Drop it into your server's plugins/ folder.
3Start once, add your license to loader.yml (see License below), then restart.
4Once it is verified, tune config.yml to taste and run /dw reload.

Where things live

plugins/DupeWatch/

loader.ymlYour license key (the Lukittu loader reads this)

config.ymlPlugin settings: scanning, Discord, Money Watch

messages.ymlEvery GUI title, button and message

watchlist.jsonYour watch rules

data.dbThe SQLite database (default storage)

cases/Exported investigation cases

Activation

License & Activation

DupeWatch is protected by the Lukittu loader. After you buy, you collect your license key from our Discord, drop it into loader.yml, and restart. Updates take care of themselves after that.

Getting your license key

Keys are handed out in our Discord, not at checkout.

1. Buy DupeWatch
Grab it on BuiltByBit or VoxelShop.
2. Open a Discord ticket
Join our Discord, open a ticket, and post your proof of purchase.
3. Receive your key
A staff member sends your license key right there in the ticket.

Open a ticket in Discord

Once you have your key, open plugins/DupeWatch/loader.yml and paste it in:

plugins/DupeWatch/loader.yml

# Lukittu Loader Configuration
license-key: "XXXX-XXXX-XXXX-XXXX"

Then restart your server. The loader checks the key on startup and pulls the plugin down once it is valid. A plain /dw reload will not re-run the loader, so use a full restart for this step.

How the loader works

Your download is a secure Lukittu loader. On startup it verifies your license, then loads and runs the real DupeWatch inside a protected environment. That is what keeps the plugin safe from leaks and lets new versions ship to you automatically.

Where to buy

BuiltByBit VoxelShop

Keep your key private

Treat your license key like a password. Share it only inside your own Discord ticket, never in public channels, logs or screenshots.

No commands needed

The GUI System

A clean point and click interface across 15 screens. Your staff can run the whole workflow without typing a single command.

Main Menu

Central hub. Jump to every feature.

Watchlist

Browse, add and manage watch rules.

Add Rule

Add the item in your hand as a new rule.

Edit Rule

Tune thresholds, scope, severity and actions.

Scan Player

Pick a player and run a manual scan.

Cases

All active investigation cases, searchable.

Resolved Cases

Browse closed cases, searchable.

Case View

Evidence, notes, confiscate and export.

Player Cases

Every case for a specific player.

Settings

Adjust plugin behaviour on the fly.

Inventory Snapshot

A frozen snapshot of an inventory.

Live Inventory

Watch a player's inventory in real time.

CoreProtect Context

Browse forensic data in-game.

Confirmation

A safety gate for destructive actions.

Search anything

Use the compass at the bottom of the Cases and Resolved Cases screens to search by player name (left click) or by Case ID (right click).

The heart of DupeWatch

Watchlist & Rules

A rule says what to watch for and what happens when it triggers. You build one straight from the item in your hand, all through the GUI.

add a watch rule

1 / 5

NTH

Hold the item

Put the item you want to watch in your main hand.

Rule settings

Threshold: How many matching items before it triggers (say 30).
Time window: The rolling window, in seconds, that counts toward the threshold.
Scope: inventory, inventory+ender, or everywhere.
Severity: low, med or high. Drives alert urgency and the Discord colour.

Added from the GUI

There is no instant command to add a rule. You hold the item, open /dw, and click Add From Hand in the Watchlist. That captures the item's exact fingerprint.

threshold tuning

Trigger threshold30 items / 60s

Items seen this window18

Under threshold, so nothing happens.

scan scope

Inventory

Main + hotbar

scanned

Ender chest

Per-player vault

scanned

Nested containers

Shulkers & bundles

Actions when a rule fires

ALERT_STAFF

Send an in-game alert to all online staff.

LOG_CASE

Open a full investigation case.

DISCORD_WEBHOOK

Fire a Discord alert via webhook.

RUN_COMMANDS

Run configured commands (ban, jail, notify…).

CONFISCATE_OPTIONAL

Enable the confiscate option on the case.

The engine

Scanning & Detection

DupeWatch identifies duplicated items with semantic fingerprinting and watches how stacks grow over time, so it keeps catching dupes even after a Minecraft update.

live scan · Netherite Ingot

count / scan cycle

scan #1threshold: 30 / 60sscan #6

Fingerprinting items and tracking growth across scan cycles…

material:netherite_ingotname:§6Tycoon Barlore[2]enchants{}custom_model:14502pdc(filtered)

················

The same logical item hashes identically across Minecraft versions, so dupes are still caught after an update.

manual scan

CBL

DIA

NTH

EMR

STN

GLD

NTH

DIA

AME

NTH

IRN

RED

detection pipeline

item

Material filter

Bloom filter

Fingerprint

Match

Most items are rejected in microseconds before any heavy work happens.

Fingerprint matching

It compares type, name, lore, enchants, custom model data and filtered PDC, not raw bytes.

Growth patterns

It flags items multiplying across scan cycles, not just a high count on its own.

Bloom filters

Sub-microsecond material pre-filtering skips items it does not care about instantly.

Dirty-flag scanning

It only scans inventories that actually changed since the last cycle.

Rate limiting

Global alert caps and per-rule cooldowns stop alert spam before it starts.

Smart de-duplication

It avoids opening noisy duplicate cases for the same underlying issue.

Investigations

Case Management

Every triggered rule opens a case with a full lifecycle. Work them in-game or wherever your staff are most comfortable.

case #4F2A

Status

New

Case opened automatically from a rule trigger.

Review

See the evidence, the player, the flagged items and the forensic context.

Annotate

Drop staff notes on any case so the next person has the full story.

Export

Save a case to JSON for your records or an external review.

Resolve

Close it out. Resolved cases stay searchable and can be reopened.

Nothing is ever lost

Resolved cases move to their own searchable tab and can be reopened if new evidence shows up. The history sticks around for audits.

Clean up

Quarantine & Confiscation

Pull duped items out of circulation safely, and hand back any false positives as fully legitimate items with no leftover flags.

confiscation

Quarantine: 0

NTH×64

DIA

I confirm removal of 3 flagged stacks

Confiscate

Remove flagged items from a player's inventory and ender chest, behind a confirmation gate.

Quarantine

Hold seized items for review instead of deleting them. Hand them back later if the player is cleared.

Identity regeneration

Returned items get fresh IDs and cleared flags, so they behave just like newly spawned legit items.

No re-flag loop

Because returned items are re-minted, a cleared player can use them normally without instantly tripping detection again, while the case history is kept for audits.

Integration

Discord Alerts

Real time alerts in your staff channels, kept deliberately to high signal events so your channels stay clean and actually useful.

DupeWatchApptoday at 14:32

New Investigation Case

Player

Steve_92

Severity

High

Item

Netherite Ingot ×68

Rule

netherite_watch

DupeWatch · Case #4F2A · today at 14:32

Click a severity to see how the embed recolours.

config.yml

discord:
  enabled: true
  webhookUrl: "YOUR_WEBHOOK_URL"
  override: false           # true routes ALL rules through this webhook
  webhook:
    username: "DupeWatch"
    colors:
      low: 0x00FF00         # green
      med: 0xFFA500         # orange
      high: 0xFF0000        # red

Per-rule webhooks

Route important items to their own channel, or send everything through one global webhook.

Role pings

Optionally ping a staff role on high severity cases so nothing slips by.

/dw testwebhook <fingerprint>

check delivery

Economy

Money Watch

Vault integration that watches for suspicious economy activity, like the tell tale balance spikes that tend to follow a dupe.

balance / time

Steady earning curve. Nothing to see here.

Anomaly detection

It flags sudden balance spikes, doubling and abnormal growth rates.

Balance tracking

It keeps a rolling history of balance snapshots for trend analysis.

Your thresholds

Set the minimum amount, the doubling threshold and the growth rate limit.

config.yml

moneywatch:
  enabled: true
  pollIntervalSeconds: 5
  anomaly:
    minAmountThreshold: 100.0
    balanceDoublingThreshold: 2.0
    growthRateThreshold: 5.0

Spatial intel

Activity Heatmaps

See where suspicious activity clusters on your server, then jump straight to it.

activity heatmap

Nether hub

120 / 64 / -340

Teleport here

Click a hotspot. Staff can warp straight to the busiest areas.

Location tracking

It records where flagged events happen across your worlds.

Heat visualization

Aggregated activity makes the hotspots obvious at a glance.

Teleport to hotspots

Staff with dupewatch.heatmap.teleport warp straight to the busiest areas.

Forensics

CoreProtect Integration

When a case opens, DupeWatch pulls in the surrounding forensic context from CoreProtect, so your staff see the whole story at a glance.

CoreProtect context

-0:42Broke a spawner

-0:31Opened a double chest

-0:18Placed 3 shulker boxes

-0:05Said "dupe stack" in chat

0:00DupeWatch flagged the inventory

Automatic context

It pulls the player's actions from around the time of the flag: block, container, chat and command history.

Built-in browser

An interactive GUI lets staff browse that forensic data right in-game.

Hybrid storage

It captures both the first and the latest context for thorough, time-aware investigations.

Requires CoreProtect

Install CoreProtect to switch this on. There is no extra DupeWatch config to touch, it just lights up.

Item tracking

Item Identity Engine

It tracks how individual item stacks move across your server, so you can see exactly how a dupe spread.

item spread

StSteve

AlAlex

BoBob

MiMia

KaKai

The identity engine traces every hand a duped item passes through.

Stack IDs

Unique IDs are minted into item stacks using Persistent Data Containers.

Ownership registry

It tracks who has held an item and when, building a chain of custody.

Spread graph

It maps how duplicated items propagate from player to player over time.

Version independent

Fingerprints are built from semantic item fields, so the same item hashes identically on 1.21.5 and 26.x. Dupes are still caught after a Minecraft update.

Built for scale

Performance

DupeWatch is built for busy servers. The optimizations are on by default and manage themselves.

main-thread CPU

~85%80% lighter

Caching, bloom filters and dirty-flag scanning keep the main thread quiet.

0%+

CPU reduction

<0.00ms

Event handling

Fingerprint cache

5 min TTL

0%+

Cache hit rate

typical

Server size	Cache hit rate	Memory	CPU reduction
Small (1 to 50)	85 to 90%	under 30 MB	75 to 80%
Medium (50 to 200)	90 to 95%	30 to 40 MB	80 to 85%
Large (200+)	90 to 95%	40 to 50 MB	80 to 85%

Watch it live

Run /dw stats or turn on debug.enabled to see cache hit rates and any slow operation warnings.

Reference

Commands

Most of the work lives in the GUI, but every action has a command for power users and automation. The base command is /dupewatch, with /dw as a shortcut.

Command	What it does	Permission
`/dw`	Open the main DupeWatch GUI, the hub for everything.	review
`/dw scan <player>`	Run a manual scan of a player's inventory and ender chest.	scan
`/dw case <caseId>`	Open a specific investigation case in the GUI.	review
`/dw note <caseId> <text>`	Attach a staff note to a case.	review
`/dw resolve <caseId>`	Mark a case as resolved.	admin
`/dw exportcase <caseId>`	Export a case to JSON for external review.	review
`/dw webhook <fingerprint> <url>`	Set a per-rule Discord webhook URL.	admin
`/dw testwebhook <fingerprint>`	Send a test Discord webhook for a rule.	admin
`/dw stats`	Show live performance and cache statistics.	review
`/dw reload`	Reload config, messages and the watchlist.	admin

Rename the command

You can rename /dw to anything you like (say /antidupe) from the command section of config.yml. That one needs a full restart, not just a reload.

Reference

Permissions

Granular nodes let you hand staff exactly what they need. Here are some sensible preset groups.

Permission node	Grants	Default
`dupewatch.review`	View the GUI, cases and evidence	op
`dupewatch.admin`	Manage rules and destructive actions	op
`dupewatch.scan`	Run manual scans	op
`dupewatch.alerts`	Receive in-game staff alerts	op
`dupewatch.confiscate`	Confiscate suspicious items from cases	op
`dupewatch.heatmap.teleport`	Teleport to heatmap hotspots	op
`dupewatch.containerwatch.view`	View container watch logs	op
`dupewatch.containerwatch.clear`	Clear container watch logs	op
`dupewatch.moneywatch.view`	View Money Watch status and graphs	op
`dupewatch.bypass`	Exempt a player from all detection	false
`dupewatch.payall.bypass`	Bypass pay-all mass payment detection	false

Administrators

adminreviewscanalertsconfiscate

Staff and moderators

reviewscanalertsconfiscate

Trusted players

bypass

Reference

Configuration

Almost everything is configurable through config.yml (750+ lines) and messages.yml (460+ lines). The essentials are below, and every option ships with inline comments.

Database

config.yml

database:
  sqlite:                  # the default, no setup needed
    filename: "data.db"
  mysql:
    enabled: false         # flip to true for MySQL + HikariCP pooling
    host: "localhost"
    port: 3306
    database: "dupewatch"
    user: "dupewatch"
    password: "password"
  migration:
    autoMigrateOnStartup: true   # moves file data into the DB, originals kept
  backup:
    enableAutoBackup: true       # auto backup before upgrades

Scanning

config.yml

scan:
  maxItemsPerScan: 1000     # cap items scanned per player
  onlyDirty: true           # only scan inventories that changed
  sampleFraction: 0.1       # also re-check 10% of "clean" players
  maxConcurrentScans: 5     # parallel scan cap
  minimumScansForDetection: 5
  growthDetection:
    doublingThreshold: 0.15
    triplingThreshold: 0.20

Money Watch

config.yml

moneywatch:
  enabled: true
  pollIntervalSeconds: 5
  anomaly:
    minAmountThreshold: 100.0
    balanceDoublingThreshold: 2.0
    growthRateThreshold: 5.0

Apply changes instantly

Most settings hot reload with /dw reload. The config-version field is managed for you, so do not edit it by hand.

Help

Troubleshooting

Quick fixes for the things people hit most often. Still stuck? Our support team is one click away.

Questions

Frequently Asked

Ready to lock down your economy?

Set DupeWatch up in minutes and run the whole thing from the in-game GUI.

Get support

DupeWatchWiki

What is DupeWatch?

Smart scanning

Growth detection

Case management

15-screen GUI

Discord alerts

Built for scale

Quick Start

Install the loader

Add your license

Make your first rule

Try it out

Installation

Requirements

Server software

Java runtime

Storage

Soft deps

Steps

Where things live

License & Activation

The GUI System

Watchlist & Rules

Rule settings

Actions when a rule fires

Scanning & Detection

Fingerprint matching

Growth patterns

Bloom filters

Dirty-flag scanning

Rate limiting

Smart de-duplication

Case Management

Review

Annotate

Export

Resolve

Quarantine & Confiscation

Confiscate

Quarantine

Identity regeneration

Discord Alerts

Per-rule webhooks

Role pings

Money Watch

Anomaly detection

Balance tracking

Your thresholds

Activity Heatmaps

Location tracking

Heat visualization

Teleport to hotspots

CoreProtect Integration

Automatic context

Built-in browser

Hybrid storage

Item Identity Engine

Stack IDs

Ownership registry

Spread graph

Performance

Commands

Permissions

Configuration

Database

Scanning

Money Watch

Troubleshooting

Frequently Asked

Ready to lock down your economy?

DupeWatch
Wiki