# Chainlink

To use this relay, it is necessary to have [LINK](https://docs.chain.link/resources/link-token-contracts) tokens on the client contract, as they are utilized for payment transfers on the Chainlink contract side.

Furthermore, it is necessary to add the token address on the client contract, which will be used for the transfer payment (see the table below). This is done by calling the following method on the client contract:

```solidity
function setFeeToken(IERC20 _feeToken) public onlyOwner
```

The method accepts the following parameters:

* **\_feeToken** - a mandatory parameter, token address for paying the transfer fee.

### Lists of supported networks

{% content-ref url="/pages/wZFtXe6DPFG2bCxCeChC" %}
[Mainnet](/guides/external-relays/list-of-external-relays/chainlink/mainnet.md)
{% endcontent-ref %}

{% content-ref url="/pages/8nt4xfftZylFv8XoPnxb" %}
[Testnet](/guides/external-relays/list-of-external-relays/chainlink/testnet.md)
{% endcontent-ref %}


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