How to Sell Crypto From a Wallet App

On 5 September 2023, MetaMask launched a Sell button inside its Portfolio web app. It handled one asset, ETH on Ethereum mainnet, in a handful of markets, and paid out dollars, pounds or euros to a bank account or a PayPal balance.

MetaMask itself bought nobody's ether: press Sell in a wallet app, then or now, and the app passes you to a separate payments company that quotes a price, checks who you are, receives your coins and sends the money. Blockworks' launch report named four off-ramp providers behind that first button, and Banxa was one of them.

This guide walks through the flow in generic stages rather than any app's current screens. It is educational material, not financial advice.

Who is on the other side of the trade

A self-custody wallet is software that holds your keys and signs transactions for you. It has no bank account to pay you from.

Turning crypto into money means banking partners, identity checks, fraud controls and licences in each market served, which is a whole business that most wallet makers do not want to run. So the cash leg is handed to a provider, and the provider is your counterparty: it buys the coins and it pays you. The wallet is the interface that finds the provider, prepares the transfer and asks you to sign it.

The five steps of an in-wallet sale

1. Region and amount. The app asks where your bank account is registered, because that decides which providers and currencies can serve you, and then you enter how much to sell.

2. Pick a quote. One or more providers answer with a price, and the figures refresh as the market moves.

3. The provider's own pages take over next, where a first-time seller may have to verify their identity there and add the bank account that will receive the payout.

4. Sign the transfer. Back in the wallet, a transaction is waiting, pre-filled with your coins and a deposit address the provider supplied with the order, and you approve it with your own key.

5. Finally the provider watches the chain, waits until your deposit has enough blocks on top of it to count as settled, and pays out over a bank rail.

Step four trips people up, because it is an ordinary on-chain send, the same kind you would make to a friend, and it is final once confirmed. There is no undo. Nobody, including the wallet maker, can pull it back if it goes to the wrong address or the wrong network.

What the provider sees and what stays with you

Your keys never leave the wallet, and no step in a legitimate sale asks for your seed phrase, so a page that does is a red flag whoever it claims to be.

The provider, by contrast, sees a great deal: your name and documents, your bank details, the address you sent from and the amount. The wallet app passes over the order basics and gets status updates back. MetaMask's integration documentation shows the shape of it, with the provider's deposit address travelling back to the wallet inside the order details so the send can be pre-filled.

Neither party can move coins out of your wallet without your signature. That is the whole point of keeping the transfer as a separate step you have to approve.

Why the price can move after you sign

A quote is a price for a moment. MetaMask describes its quotes as refreshing automatically to track the exchange rate, which is a polite way of saying the number on screen is always provisional.

The provider does not have your coins until the transfer confirms, and the market keeps trading in the meantime. Ethereum opens a new block slot every 12 seconds, so a send paying a competitive fee is usually picked up quickly, but one paying too little can sit unconfirmed for a long while. If the deposit lands late, or for a different amount from the order, it may be re-priced at the rate on arrival or sent back, and the provider's terms say which.

Read that clause before you sign.

Selling a token still costs the chain's own coin

This one catches people out: every Ethereum transaction pays its fee in ether, whatever it is moving. Ethereum's developer documentation is blunt about it: gas is paid in ETH, and it is charged whether the transaction succeeds or fails.

So a wallet full of stablecoins and no ETH usually cannot complete a sale on Ethereum mainnet, because the transfer to the provider cannot be paid for. The exception is a wallet that covers the fee itself and charges it back in a token such as USDC. Even a plain ETH send uses 21,000 units of gas.

Selling your entire ETH balance has its own snag, because gas has to come from somewhere: the fee is drawn from the same balance, so the most you can send is slightly less than everything you hold. Most other chains work the same way, charging fees in their own native coin.

When the money arrives

The bank rail sets the pace: MetaMask's help centre says payouts over SEPA in Europe and Faster Payments in the UK can land as soon as the provider finishes processing, while US bank transfers may take one to three business days.

If the order shows as complete but the money has not appeared after a few days, the provider is the one to contact, since it executed the sale and holds the payout record, and the wallet only ever saw the transfer.

At launch, MetaMask said it planned to extend Sell to the gas tokens of layer-2 networks. Its help centre now says supported networks and tokens vary by country, which is the honest answer for every wallet with a Sell button: what you can sell, and where the money can go, depends on which providers serve your region. Selling through an exchange account is a separate route, with its own deposit and withdrawal steps.