Viper Economy

Viper Economy is a server-side Fabric economy mod for Minecraft 1.21.x, 26.1.x, 26.2.x and 26.3.x. It adds virtual or physical currency, a server shop GUI, player chest shops, player-to-player payments and purchasable command rewards (claim blocks, ranks, kits). No client mod is needed: vanilla clients can join and use everything, and the mod also works in singleplayer.

Features

• Virtual currency (number balances stored per player) or physical currency (an item such as diamonds used as money).
• Server shop GUI with categories, pagination, per-item buy/sell prices, shift-click bulk buy/sell and a configurable purchase tax.
• Player chest shops: attach a sign to a chest to sell its contents, with ownership protection so other players cannot open shop chests.
• Player-to-player payments, balance leaderboard and held-item price checks.
• Command rewards: any shop entry can run console commands on purchase, for example giving claim blocks or a LuckPerms rank, with or without handing over a physical item.
• New accounts automatically receive the configured starting balance. Balances are saved to disk on every change and on server shutdown.
• A daily cap on how much each player can earn from selling, to slow inflation.

Commands

Player commands

Players can also use the shop GUI directly: left-click buys 1, shift-left-click buys a stack, right-click sells 1, shift-right-click sells everything of that item.

Admin commands (server operators only)

Configuration

All files live in config/viper-economy/ on the server. config.json is created with defaults on first start. prices.json (500+ entries) is auto-deployed on first start; every registered item appears in the shop, with unpriced items listed as catalog-only until you set prices.

config.json

prices.json

Each shop entry maps an item id to its category, transaction stack size, buy price and sell price. A price of 0 means that direction is disabled.

"minecraft:diamond": {
    "category": "gems",
    "stack": 64,
    "unit_buy": 100.0,
    "unit_sell": 50.0
}

Categories map a key to a display name and a display item:

"rewards": {
    "name": "Server Rewards",
    "display_item": "minecraft:nether_star"
}

Command rewards (claim blocks, ranks, kits)

"minecraft:nether_star": {
    "category": "rewards",
    "stack": 1,
    "unit_buy": 5000,
    "unit_sell": 0,
    "give_item": false,
    "commands": ["claimblocks {player} add 1000"]
}

"minecraft:enchanted_golden_apple": {
    "category": "rewards",
    "stack": 1,
    "unit_buy": 10000,
    "unit_sell": 0,
    "give_item": false,
    "commands": ["lp user {player} parent add vip"]
}

Commands run as console with full permissions, and the buyer sees a "Rewards applied!" message. Reward entries show a "Grants perks on purchase" lore line in the shop. Works from both the GUI and /buy.

Chest shops

Player-run shops that trade items for balance money. No sign writing is needed: you build the chest and sign, then link them with a command.

Setup, step by step

1. Place a chest (single or double) and attach a wall sign directly to it. Standing signs do not work.
2. Put at least one of the item you want to trade into the chest. The sold item is auto-detected from the first non-empty chest slot.
3. Look at the sign (within 5 blocks) and run /shop create buy <price> to sell to customers, or /shop create sell <price> to buy from customers.
4. The sign is rewritten automatically and the shop opens for business. Restock the chest as it sells out.

The /shop commands

Creating and removing your own shops needs no special permission. One sign and one chest can each belong to only one shop, and an empty chest cannot become a shop.

Sign layout (written automatically)

How trading works

• BUY shop: the customer must have enough balance, then 1 item leaves the chest stock, 1 item is given to the customer, the price moves from the customer to the owner (credited even while the owner is offline), and the sign-side display updates.
• SELL shop: the customer must carry the traded item, the chest must have a free slot, and the owner must afford the price. Then 1 item moves from the customer into the chest and the price moves from the owner to the customer.
• Every click trades exactly 1 item. There is no sales tax and no daily sell limit on chest trades.
• Only the owner and server operators can open a shop chest. Other players are blocked with a message when they try.
• Shops are stored in config/viper-economy/shops.json and survive restarts.

Installation

1. Install Fabric Loader (0.14.21 or newer on 1.21.x, 0.19.3 or newer on 26.x) and Fabric API for your Minecraft version. Use Java 21 for 1.21.x and Java 25 for 26.x.
2. Download the file below that matches your Minecraft version (1.21.x, 26.1, 26.2 or 26.3).
3. Put the jar in the server mods folder and start the server once. This generates config/viper-economy/config.json and prices.json.
4. Edit the prices to taste. Most changes apply without a restart.

Notes

• Storage is plain JSON files under the server config folder. No database needed.
• The 1.21.x build runs on 1.21 through 1.21.11.
• Requires Fabric API (any version for your Minecraft release).