> For the complete documentation index, see [llms.txt](https://v3.docs.pooltogether.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://v3.docs.pooltogether.com/master-1/protocol/tokens/token-listener.md).

# Token Listener

The Token Listener interface allows contracts to "listen" to the complete token lifecycle of mint, transfer and burn.  There are two functions that must be implemented: `beforeTokenMint` and `beforeTokenTransfer`

The beforeTokenMint function must be called whenever a token is minted.

```javascript
function beforeTokenMint(
    address to,
    uint256 amount,
    address controlledToken,
    address referrer
) external;
```

| Paramater Name  | Parameter Description                                 |
| --------------- | ----------------------------------------------------- |
| to              | The address that is receiving the newly minted tokens |
| amount          | The amount of new tokens                              |
| controlledToken | The token being minted                                |
| referrer        | The address that referred the user (for rewards)      |

The beforeTokenTransfer function must be called whenever a token is transferred or burned.

```javascript
function beforeTokenTransfer(
    address from,
    address to,
    uint256 amount,
    address controlledToken
) external;
```

| Paramater Name  | Parameter Description                                                      |
| --------------- | -------------------------------------------------------------------------- |
| from            | The address that is sending the tokens                                     |
| to              | The address that is receiving tokens.  May be the zero address if burning. |
| amount          | The amount of tokens                                                       |
| controlledToken | The token being transferred                                                |