Fund an app or agent to send messages with XMTP

Self-fund a payer wallet

Step 1. Create the payer wallet

The payer wallet must be:

• A standard Ethereum-compatible wallet account
• Non-custodial, meaning you control the private key (not a third-party service)
• Able to sign and transact on the Base and XMTP App Chain networks
• Able to hold and transfer USDC tokens

You can create a payer wallet using common non-custodial wallet apps, such as Coinbase Wallet and MetaMask.

Payer wallets can be funded by Ethereum EOAs and smart contract wallets. For example, a Gnosis Safe or any ERC-1271 wallet can deposit funds into a payer account using the Funding Portal.

You'll need your payer wallet's private key when setting up your XMTP Gateway Service.

Step 2. Register the payer wallet

1. Use your payer wallet to connect to the XMTP Funding Portal → testnet link coming soon.
2. On the Welcome page, click Use connected wallet.
3. Open the drop-down menu in the upper right and click Manage payers.
4. Click the pencil icon to give your payer wallet a human-readable name.
5. Click the green check button to save.

Your payer wallet is now a payer in the Payer Registry smart contract.

Step 3: Fund the payer wallet with USDC on Base

Fund your payer wallet with USDC on Base. Here are some sources you can use to acquire USDC:

• Centralized exchanges: Binance, Coinbase, Kraken
• Direct purchase: Circle, Coinbase
• Business accounts: Circle business accounts for larger operations

To get USDC on Base Sepolia for use with XMTP testnet, you can use https://faucet.circle.com/, which provides 10 USDC per hour.

Step 4: Allocate funds for messaging

The XMTP Funding Portal will accept only testnet USDC until November 1, 2025. Plan your testnet and mainnet funding accordingly.

1. Connect the payer wallet to the XMTP Funding Portal → testnet link coming soon.
2. In the drop-down menu in the upper right, be sure to select the payer wallet.
3. On the Dashboard page, click Fund.
4. Enter the amount of USDC you want to allocate from your payer wallet.
5. The XMTP Funding Portal automatically optimizes how the funds are allocated to cover messaging fees and gas fees. Expand the Transaction details area to view the details of the split.
6. Click Continue.
7. The Depositing funds screen displays. You can click Cancel transaction to attempt to cancel the transaction, if needed.

Your payer wallet now has:

• USDC allocated to your registered payer wallet in the Payer Registry smart contract. This allowance will be used to pay XMTP Broadcast Network messaging fees.
• USDC bridged to your payer wallet on the XMTP App Chain. This balance will be used to pay XMTP App Chain gas fees.

You can use the payer wallet (and only the payer wallet) to withdraw USDC from your messaging fee allowance.

Step 5: Monitor your usage and allowance

You can use the Usage panel on the XMTP Funding Portal Dashboard to review the number of messages sent by your app, as well as actual and projected fees.

Before data can display in the Usage panel, you must have completed the following on the appropriate network (testnet or mainnet):

1. Deployed your XMTP Gateway Service
2. Updated your app to use a compatible XMTP SDK
3. Sent messages using your app

We recommend funding an allowance for 3-6 months of estimated usage.

If your allowance goes to zero, the Payer Registry smart contract rejects new messages sent to the XMTP Broadcast Network and returns an INSUFFICIENT_PAYER_BALANCE error.

Step 6: Withdraw and claim funds

You can use the payer wallet (and only the payer wallet) to withdraw USDC from its messaging fee allowance at any time.

• Withdrawals that require bridging will be available after 7 days and require a second transaction to claim.
• Withdrawals without bridging will be available after 48 hours and require a second transaction to claim.

1. Connect your payer wallet to the XMTP Funding Portal → testnet link coming soon.
2. On the Dashboard page, click Withdraw.
3. Enter the amount of USDC you want to withdraw from your messaging balance. Click MAX if you want to withdraw the maximum amount available.
4. Click Request withdrawal.
5. After the required wait time, return to the XMTP Funding Portal to complete your withdrawal. On the homepage, view the Transaction panel and locate your Withdrawal and Bridge transactions. The Status column should be set to Ready to withdraw.
6. Click Ready to withdraw to display the Transaction details panel.
7. Verify the withdrawal details and click Claim USDC.

Fund a payer wallet using another wallet

Step 1. Get the payer wallet address

To fund an app using a wallet other than its payer wallet, you need the payer wallet address.

Step 2. Select the payer wallet you want to fund

1. Use the wallet you want to use to fund the payer wallet to connect to the XMTP Funding Portal → testnet link coming soon.
2. On the Welcome page, click Use other wallet.
3. On the Manage payer wallets screen, enter the payer wallet address you want to fund and a human-readable display name.
4. Click the green check button to save.

Your wallet can now fund the payer wallet.

Step 3: Deposit USDC into your wallet

Deposit USDC into your wallet on Base. This is the wallet you want to use to fund the payer wallet.

Here are some sources you can use to acquire USDC:

• Centralized exchanges: Binance, Coinbase, Kraken
• Direct purchase: Circle, Coinbase
• Business accounts: Circle business accounts for larger operations

To get USDC on Base Sepolia for use with XMTP testnet, you can use https://faucet.circle.com/, which provides 10 USDC per hour.

Step 4: Allocate funds to the payer wallet

The XMTP Funding Portal will accept only testnet USDC until November 1, 2025. Plan your testnet and mainnet funding accordingly.

1. Use the wallet you funded in Step 3 to connect to the XMTP Funding Portal → testnet link coming soon.
2. In the drop-down menu in the upper right, be sure to select the payer wallet.
3. On the Dashboard page, click Fund.
4. Enter the amount of USDC you want to allocate from your wallet to the payer wallet.
5. The XMTP Funding Portal automatically optimizes how the funds are allocated to cover messaging fees and gas fees. Expand the Transaction details area to view the details of the split.
6. Click Continue.
7. The Depositing funds screen displays. You can click Cancel transaction to attempt to cancel the transaction, if needed.

The payer wallet now has:

• USDC allocated to the registered payer wallet in the Payer Registry smart contract. This allowance will be used to pay XMTP Broadcast Network messaging fees.
• USDC bridged to the payer wallet on the XMTP App Chain. This balance will be used to pay XMTP App Chain gas fees.