Check token approvals before you bridge

Before bridging a token, check which contract your wallet is allowing to spend it and how much it can spend. A token approval is permission for a contract to move a token from your wallet; it does not, by itself, send the token across a bridge. The bridge may need that permission to lock or burn tokens on the source network before a matching asset is released or created on the destination network.

Why does a bridge ask for token approval?

Most tokens do not let a bridge move them from your wallet automatically. The token’s contract keeps an allowance—a limit on how many tokens another contract may spend. You set or change that allowance in a wallet transaction, which usually needs a network fee.

The approval and the bridge transfer are often separate steps. First, you authorize the bridge contract to use the token; then you submit the transfer. Some interfaces combine steps, so read each wallet prompt. For a closer look at the token’s path, see this fuller explanation of what Mantle Bridge does to tokens.

Should you approve an exact amount or an unlimited one?

An exact approval covers the amount you plan to bridge. It can mean another approval transaction next time, but it limits how much the contract is allowed to spend under that permission. An unlimited approval can save a step on later transfers, but it leaves a larger allowance in place until it is changed or used.

For most occasional transfers, approving only the amount you need is the simpler choice. If you choose a larger allowance for convenience, remember that it can remain after the transfer. A completed bridge does not necessarily remove the permission.

• Check that the token and source network match the transfer you intend to make.
• Read the spender address shown in your wallet and compare it with the bridge interface you opened.
• Check the approval amount; pause if it is much larger than your planned transfer.
• Review old allowances from time to time and reduce ones you no longer need.

What should you check before signing?

Read the approval prompt before confirming it. Make sure you are on the network holding the tokens, the token is the one you intend to bridge, and the spender is the contract named for that bridge action. If the wallet shows an amount or address you cannot match to the transfer, stop and check the bridge details before signing.

Changing an allowance usually requires another transaction and a network fee. Reducing it does not reverse a transfer that already happened, and it does not retrieve tokens sent to the wrong address. Treat an approval as an ongoing permission, then check it again if you return to bridge later. Watch the spender and amount in the wallet prompt each time, especially when the token or source network changes.