> For the complete documentation index, see [llms.txt](https://docs.certhis.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.certhis.io/smart-contract/contract-checker.md).

# Contract Checker

With this functionality, available on Certhis Business Manager,  you can establish customized rules to filter mints in your collection.

<figure><img src="/files/k0wbeUvK5eZU0bgoy64F" alt=""><figcaption></figcaption></figure>

Example: \
\- If the transaction initiator is blacklisted on the USDT (TETHER) contract. \
\- Verify whether the transaction initiator owns a specific NFT ...\ <br>

This is the interface of the contract checker

```
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;

/**
 * An interface for the Icerthis_check contract.
 * Defines the necessary function for checking the validity between two addresses.
 */
interface Icerthis_check {
    /**
     * Function to check the validity or a specific condition between two addresses.
     * The implementation of this function would typically involve some form of verification logic.
     * @param _address The first address to be checked.
     * @param _address2 The second address to be checked.
     * @return A boolean value indicating the result of the check. True if the check passes, false otherwise.
     */
    function check(address _address, address _address2)
        external
        view
        returns (bool);
}
```