A forensic-grade item-duplication detector for Paper, Folia and Spigot servers.
Most anti-cheat plugins focus on movement, reach and combat exploits. AntiDupePro focuses on a category they usually ignore: the steady drip of duped items that silently inflates your server's economy. It does this by writing an append-only, tamper-evident ledger of every item movement and reconciling each player's actual inventory against what the ledger says they should hold.
If something doesn't add up, you get an alert before the dupe spreads.
Compatibility
| Server software | Paper, Folia, Spigot, and Paper-compatible forks (Purpur, Pufferfish, etc.) |
| Minecraft versions | 1.21.x (main branch) · 26.x (paper-26 branch) |
| Java | 21+ for 1.21.x · 25+ for 26.x |
| External services | None required (SQLite is bundled). Redis is optional for multi-server networks. |
What it catches
A non-exhaustive list of dupe families AntiDupePro detects:
- Stack-clone exploits — click-timing, cursor desync, drag-and-place tricks
- Shulker / bundle laundering — recursive content scan at any nesting depth
- Item frame dupes — piston-into-frame, chunk-race, end-crystal interaction variants
- Entity inventory dupes — horses, donkeys, llamas, chest boats, chest minecarts
- Hopper laundering — items passing through automation are scanned
- Workstation outputs — smithing, anvil, loom, stonecutter, cartography, grindstone, furnaces
- Container transfers — chests (single and double), barrels, ender chests, lecterns, decorated pots — recorded by what actually moved, so shift-clicks, number-key swaps, double-click gathering and drags are all measured exactly
- Villager trades & enchanting — buying a tracked item or enchanting a book is credited properly
- Chunk-load entity respawn — the "same item entity picked up twice" family
- Drop-pickup race — same-NBT dupes via item-entity persistence
- Acquisition-rate abuse — TMAR (Theoretical Max Acquisition Rate) thresholds per material
- Witness-less acquisitions — Proof of Witness flags players whose actions are never seen by others
Full coverage matrix and the rare edge cases are documented in the user guide.
How it works
Every tracked item carries the owner's UUID in NBT — items still stack vanilla-style.
Every gain and loss event (mine, craft, pickup, container put/take, frame put/take,
workstation output, etc.) is recorded as a SHA-256-linked ledger entry. The chain
is tamper-evident: editing the database directly breaks the hash chain and
/adp ledger verify reports exactly where.
Reconciliation walks the player's inventory recursively — including the contents of held shulkers and bundles — and compares the total to the ledger balance. A surplus is a dupe.
Built to be false-alarm shy: actions are verified one tick after they happen (so other plugins cancelling a pickup or block place can't skew the books), items handed out by shop/kit/vault plugins are never held against the player, and every alert is gated through per-material thresholds you control.
Storage backends
Pick one, configurable in config.yml:
- SQLite (default) — file-based, persistent, zero ops. Perfect for single-server setups.
- Redis — fast and shareable across multiple servers behind a proxy.
- Memory — in-process only, lost on restart. Dev/testing only.
Installation
- Download the jar.
- Drop it into
plugins/. - Start the server. Defaults are sensible; the plugin generates
config.ymlandmaterials.ymlon first launch. - Done. Run
/adp helpin-game to see admin commands.
Commands
All commands live under /adp (aliases: /antidupe, /antidupepro).
| Command | What it does |
|---|---|
/adp ledger status | Chain tip, current suspects, system health |
/adp ledger balance <player> | Expected balances for each tracked material |
/adp ledger history <player> | Recent ledger entries |
/adp ledger witness <player> | Witness statistics and suspicion analysis |
/adp ledger suspects | List all currently flagged players |
/adp ledger reconcile <player> | Force a balance check on an online player |
/adp ledger trust <player> | Show accumulated trust score |
/adp ledger verify | Verify the entire hash chain |
Permission antidupe.admin grants all of the above and routes dupe alerts to chat.
Configuration
Three YAML files in plugins/AntiDupePro/:
config.yml— storage backend, modes (shadow / auto-delete), ledger settingsmaterials.yml— tracked materials, rate limits, alert thresholdsmessages.yml— every in-game message; fully translatable (missing keys fall back to English)
Speaks your language: English, Português do Brasil, Español, Deutsch, Русский
and Polski are built in — one language: line in config.yml switches everything.
Alerts can also be pushed outside the game: Discord, Telegram, Slack, or any
custom JSON webhook (n8n, Zapier, your own bot) — with severity filtering and
burst protection built in. See the notifications section of config.yml.
Both are documented inline. Sensible defaults; you can add your own materials to the list at any time and restart.
Free and open source
No license key, no telemetry, no "premium" gating. The source is on GitHub. Issues and pull requests are welcome.
Links
- Source / issues: github.com/darkstarworks/AntiDupePro
- User guide: gitbook/user-guide
- Notifications & translation guide: gitbook/notifications-and-translation
- Changelog: gitbook/changelog
