HMTSync

HMT Sync keeps player data consistent across your whole network. When a player moves from one server to another, their inventory, health, hunger, experience and much more are carried over automatically — no lost items, no duplicated gear, no manual work.

Works on Paper / Spigot backends with the Velocity proxy.

Features

• Seamless server switching — the proxy saves a player's data on the source server before they connect to the destination server. No race conditions, no data loss.
• No double-login exploits — a database-level lock guarantees only one server can write a player's data at a time. A crashed server is recovered automatically.
• No lag — all database work runs asynchronously in the background.
• Synchronized data (each toggled on or off):
  • Health, food level, saturation
  • Experience (total, current, level)
  • Inventory and armor
  • Ender chest
  • Potion effects
  • Advancements and statistics
  • PlayerData (PDC) values
  • Flight & gamemode, including per-gamemode inventories
  • Maps (keeps map artwork across servers)
  • Companions / pets
  • Location
• Optional Redis cache for faster server switches (SQL stays the source of truth).
• Optional economy & playtime sync via Vault and EssentialsX.
• Admin tools — in-game data inspector, manual lock release and data migration.
• Works with MySQL/MariaDB (recommended for a network) or SQLite (single server).

Requirements

• Minecraft: Paper 26.3+
• Backends: Paper or Spigot on every server that shares player data
• Proxy: Velocity 3.1+
• A shared MySQL/MariaDB database for a network (SQLite is fine for a single server)

Installation

1. Download the JAR that matches the platform:

   File	Where it goes
   hmt-sync-<version>-spigot.jar	plugins/ folder of every Paper/Spigot server
   hmt-sync-<version>-velocity.jar	plugins/ folder of your Velocity proxy

2. Start each server once so the plugin generates its plugins/HMTSync/config.yml.

3. Configure each backend — set your database credentials and give every server a unique server-id (the proxy needs no server-id).

4. Restart the proxy and all servers.

That's it — player data will now follow players between your servers.

Configuration

The important settings in plugins/HMTSync/config.yml:

database:
  type: mysql               # "mysql" or "sqlite"
  host: localhost
  port: 3306
  database: minecraft
  username: user
  password: password
  sqlite-file: "player_data.db"

# A unique name for THIS server. Every backend sharing the database needs its own.
server-id: "survival-1"

# Which data to synchronize. Turn on what you need.
sync-data:
  health: true
  food-level: true
  experience: true
  inventory: true
  armor: true
  potion-effects: true
  ender-chest: false
  location: false
  advancements: false
  statistics: false
  pdc: false
  flight-gamemode: false
  companions: false
  maps: false
  separate-gamemode-inventories: false
  economy: false
  playtime: false

# Optional Redis cache (leave disabled to use SQL only).
redis:
  enabled: false
  host: localhost
  port: 6379
  password: ""
  storage-strategy: "mysql-only"   # or "redis-mysql-hybrid"

Tips

• Give every server a different server-id (e.g. survival-1, creative, lobby).
• Keep the same database settings on every backend.
• Change security.seed to a long random string before going public.
• Newer features (ender-chest, maps, economy, playtime, …) are off by default — enable them only if you want them.

Commands

On a backend server:

On the proxy (Velocity):

Permissions

Optional integrations

• Redis — enable the hybrid cache to make server switches faster.
• Vault + an economy plugin — enable sync-data.economy to sync balances (do not enable if another plugin already syncs money).
• EssentialsX — enable sync-data.playtime to sync playtime.
• FastLogin / AuthMe — optionally auto-migrate data for cracked→premium transitions.

All integrations are optional and are simply ignored if the backing plugin is not installed.