Marketplace — server-wide trading board for Valheim

A trading board for every player on the server. Anyone can list any item from their inventory at their own price, and others can buy it — even while the seller is offline. The currency is regular Valheim coins, and every player gets a server-side bank for storing them safely.

How to use

Press F7 (configurable) to open the marketplace. Esc or F7 closes it.

Tab	What it does
BUY	All listings on the server, with search (item or seller name) and sorting. Pick a listing, set the amount (- / + / Max) and click Buy.
SELL	Items from your inventory. Pick one, set the amount and price per piece, click List for sale. The item leaves your inventory and waits for a buyer.
MY LISTINGS	Your active listings. Cancel any of them to get the item back.
MAILBOX	Items from cancelled or expired listings. Collect all moves them to your inventory.
BANK	Your coin balance and transaction history. Deposit / Withdraw a chosen amount, or everything at once.

• Sale income goes straight to your bank balance. If you are online, you get a notification.
• Purchases are paid from your balance first; if it is too low, the rest is taken from coins in your inventory.
• Bought items go straight to your inventory. If it is full, the rest is dropped next to you.
• You can buy part of a stack (e.g. 20 out of 100 wood).
• Quality, variant, durability, crafter and other mods' item data (m_customData) are preserved.
• Equipped items and coins cannot be listed.

Installation

The mod must be installed on the server and on every client. Jotunn rejects players without it.

Requirements: BepInExPack_Valheim, Jotunn 2.29.0 or newer.

1. Copy the Adrian-Marketplace folder to BepInEx/plugins/. In r2modman: profile → Browse profile folder → BepInEx/plugins.
2. On a dedicated server, copy the same folder to the server's BepInEx/plugins/.
3. Start the server once — the config file BepInEx/config/adrian.valheim.marketplace.cfg is created.

Configuration

Section	Setting	Default	Description
1 - Client	Hotkey	F7	Key that opens the window.
1 - Client	Language	English	English or Polish. Can be changed in game (e.g. with Configuration Manager).
2 - Server	FeePercent	0	Percentage deducted from the seller on each sale (0–50). The fee removes coins from the economy.
2 - Server	MaxListingsPerPlayer	25	Simultaneous listings per player.
2 - Server	ExpireHours	168	Real-time hours until a listing returns to the seller's mailbox. 0 = never.
2 - Server	MaxPricePerUnit	100000	Highest allowed price per piece.
2 - Server	BlockedItems	(empty)	Comma-separated prefab names that cannot be listed, e.g. DragonEgg,Wishbone.

Server settings are taken from the server's config file; clients receive them together with the listings.

Data and security

• The server keeps listings, mailboxes and bank balances in BepInEx/config/Marketplace/<world name>.dat. It saves after every change and keeps the previous version as .dat.bak. Each world has its own marketplace.
• Every operation is appended to BepInEx/config/Marketplace/<world name>.log: listing, purchase, cancellation, expiry, deposit, withdrawal, with the balance after the operation.
• Only the server changes balances. A withdrawal is checked against the server balance before any coins are sent.
• Players are identified by the character ID from their in-world object, not by what the client claims.
• Every rejected operation returns the item or coins.
• As everywhere in Valheim, the inventory belongs to the client. A modified client could fake a deposit or a listed item, so an anti-cheat (e.g. AzuAntiCheat) is recommended.

Building from source

Windows with .NET Framework 4 is enough (the csc.exe compiler ships with the system):

powershell -ExecutionPolicy Bypass -File build.ps1

Languages

The window is in English by default. Polish is also included: set Language = Polish in BepInEx/config/adrian.valheim.marketplace.cfg. Each player picks their own language; server messages are translated on the client side.