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Mezo Documentation

Gasless Swaps

The Get Gas feature lets you acquire a small amount of BTC to cover transaction (gas) fees on Mezo — even if you have no BTC in your wallet. It works by performing a gasless swap, exchanging a small amount of MUSD for exactly 0.0001 BTC, enough to cover multiple transactions on the network.

Because the swap is gasless (powered by meta-transactions), you don’t need any existing BTC to use it.

When Does It Appear?

Section titled “When Does It Appear?”

A “Get Gas” button automatically appears in the Mezo app when your wallet’s BTC balance drops below 0.000001 BTC. This ensures you always have a way to top up gas without needing to bridge in more BTC or use an external exchange.

Supported Tokens

Section titled “Supported Tokens”

Currently, MUSD is the supported token for Get Gas swaps. Additional tokens may be added in the future as pool liquidity grows.

How to Get Gas

Section titled “How to Get Gas”

  1. Open the Get Gas modal

    When your BTC balance is low, click the “Get Gas” button that appears in the app.

  2. Select a token

    Select MUSD as your source token. The modal will display the estimated cost for the swap.

  3. Review the quote

    The app quotes the amount of MUSD needed to receive exactly 0.0001 BTC. The output amount is fixed so you always get a predictable gas amount regardless of token price.

  4. Confirm the swap

    Click “Get Gas” to initiate the swap. You will be prompted to sign two messages in your wallet:

    • A permit signature (token approval)
    • An execute signature (swap authorization)

    No gas fee is required for these signatures.

  5. Wait for confirmation

    The app will submit your transaction and automatically poll for confirmation. Once confirmed, you’ll see a success screen with the transaction hash.

How It Works

Section titled “How It Works”

The Get Gas feature uses meta-transactions to execute the swap without requiring gas from the user:

  1. Permit: You sign an off-chain message granting the relay permission to spend the required amount of your chosen token.
  2. Relay: A backend relay service submits the swap transaction on your behalf, covering the gas cost.
  3. Swap: The transaction executes on-chain, swapping your token for 0.0001 BTC, which is deposited directly into your wallet.

This design means you can always get gas as long as you hold MUSD — no BTC needed to get started.

Key Details

Section titled “Key Details”
DetailValue
Output amount0.0001 BTC (fixed)
Eligible tokensMUSD
Gas requiredNone (gasless via meta-transactions)
TriggerBTC balance below 0.000001 BTC