# XPort Fee Center User Guide
## 1. Overview
**XPort** is the core messaging cross-chain mechanism within the Wanchain Cross-chain Bridge. In **XPort V1**, the bridge charges a certain amount of **native coin on the source chain** as a bridge fee, which is used to cover gas costs incurred when processing messages on the **destination chain**. Over the past year, XPort has seen significant growth and adoption across the blockchain community.
However, with increased usage, the V1 fee model has shown some limitations:
* The native coin charged on the source chain differs from the gas coin consumed on the destination chain;
* In volatile market conditions, the price gap between the collected and spent tokens can grow significantly, causing losses and reducing sustainability.
To address this, **XPort V2** introduces a more robust and flexible fee model:
* The **project pays in the same token** that the Agent uses to process the transaction on the destination chain;
* Projects can freely specify which token to charge end users on the source chain;
* This eliminates token price fluctuation risks and improves long-term sustainability.
## 2. Workflow
In XPort V2, when a user initiates a cross-chain message, the **cross-chain Agent** will **cover the gas fee on the destination chain**. The corresponding token amount will then be deducted from the **Fee Contract account on Wanchain**.
#### Example:
For a message from **Arbitrum to Avalanche**:
1. **Source Chain (Arbitrum)**: The user triggers the cross-chain message and pays the cross-chain fee to the project. The token used for the cross-chain fee is defined by the project.
2. **Destination Chain (Avalanche)**: The Agent pays the gas fee in AVAX, the native coin of the destination chain.
3. **Wanchain**: The equivalent AVAX amount (actual fee + platform service fee) is deducted from the Fee Contract account.
## 3. XPort Fee Center Platform
Homepage
To simplify fee management, Wanchain provides the **XPort Fee Center**, a unified portal for project teams to map their dapp contracts with spender, manage fee deposits, and check the fee spendings.
#### XPort Fee Center Access:
* **Mainnet**: [https://xport.wanchain.org](https://xport.wanchain.org/)
* **Testnet**: [https://xport-testnet.wanchain.org](https://xport-testnet.wanchain.org/)
> Please connect your wallet and ensure your network is set to **Wanchain** or **Wanchain Testnet**.
### 3.1 Asset Management
#### 3.1.1 Token Balances
This section displays the current token balance recorded in the Fee Contract for the connected wallet address.
It allows for:
* Depositing tokens;
* Withdrawing unused tokens;
* Transferring admin rights.
For example, to support cross-chain messages to Avalanche, the project team must deposit `wanAVAX` into the Fee Contract. `AVAX` is the native coin of Avalanche for gas. Other destination chains are similar, that is, **whichever token the target chain uses as gas, you should make sure the balance is enough for that minted token on Wanchain.**
#### 3.1.2 Bridge
Project teams can use WanBridge ([bridge.wanchain.org](https://bridge.wanchain.org/)) to transfer the required fee tokens to Wanchain.
#### 3.1.2 Deposit
After the required tokens are bridged to Wanchain via WanBridge, you can use the **Deposit** to fund the Fee Contract. In this way, you will be able to see the balance of the token.
**Note:** If the remaining balance in the Fee Contract is not enough to cover the user's cross-chain transaction, the transaction will remain in a pending state. Therefore, please make sure to replenish the balance in a timely manner when it is insufficient, ensuring that the Fee Contract account always has enough funds.
#### 3.1.3 Withdraw
Use **Withdraw** to retrieve any unused fees from the Fee Contract if necessary.
#### 3.1.4 Transfer Admin
Use this function to transfer admin rights of the Fee Contract to another wallet address.
### 3.2 Spenders Management
#### 3.2.1 Add Spender
A **Spender** is a DApp smart contract address on the source chain that initiates cross-chain messages.
* You must associate the contract address with the correct source chain.
* Incorrect configuration will result in stuck or failed cross-chain messages.
For example, if your DApp supports message crosschain from Wanchain to Ethereum, add the contract address to the New Spender Address and select the **Wanchain** chain as source.
#### 3.2.2 Remove Spender
If a DApp is no longer active, you could remove its contract address from the spender list.
### 3.3 Transaction History
This section displays all relevant operations and historic data, including:
* **My Deposits**
* **My Withdrawals**
* **Fee Deductions Records**
* **Admin Transfers**
## 4. Developing Cross-chain Fee Charging From End Users
The XPort Fee Center provides a comprehensive platform for unified management of payments and prepayments between the XPort protocol and the project teams. However, as a project team, you still need to develop your own contracts or tools based on your praticial DApp, so that when an end user initiates a cross-chain message on the source chain, you can collect the required cross-chain fees from the user.
For any technical questions, feel free to contact ****.
---
# Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://docs.wanchain.org/products/xport/xport-fee-center-user-guide.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.