Tokenfox teaches:

How to interact with unverified smart contracts using Etherscan

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Verified smart contracts are luckily common and easy to interact with in Etherscan. Both read and write methods from the contract are made easily available, with read ones being callable even without connecting a wallet

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But when contracts are unverified, oh no! We have no access to these convenient read/write calls!

Of course the best course of action is to find a way to get the contract verified which would expose the methods. But unfortunately, thats not always possible!

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Here's where Etherscan comes to the rescue. If you login, you will find a section called "Contract Custom ABI", that allows you to configure any contract to use any custom ABI, just for you personally:

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Here's where Etherscan comes to the rescue. If you login, you will find a section called "Contract Custom ABI", that allows you to configure any contract to use any custom ABI, just for you personally:

https://etherscan.io/mycustomabi

The largest NFT marketplace. Buy, sell, & discover the internet of goods. Get help at http://support.opensea.io. We will never DM you first.

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As an example, lets add a custom ABI to @opensea OPENSTORE tokens that are notoriously using an unverified contract

- Click in Add
- Paste in contract address
- Add ABI JSON to those methods you want to be able to access (here 'balanceOf' and 'setApprovalForAll')
- Save

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Once that is saved, navigate to etherscan page for that contract and TA-DAA! New tabs called "Read Custom" and "Write Custom" appear although the contract remains unverified!

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Let's first open "Read Custom" and try out that it works. By filling in owner and token ID, we can confirm the balanceOf check works and returns with correct info

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For the Write Custom, lets try something fun. We have a Crypto Duck token in Opensea contract that can be migrated to a new V2 on-chain contract. But doing so requires giving that contract an approval to Opensea tokens

So lets use the custom write to make that approval!

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Once the approval is made through the custom write, we can go to the Duckies V2 contract and run the migration. Which would not have been possible without using the Custom Write!

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To summarize:

We were able to interact with unverified contract with Etherscan. And in this case use that to migrate an off-chain based Opensea storefront token ID into its new fully on-chain contract. Even after the project's own migration app had already gone offline.

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Disclaimer: this is not a recommendation to invest or to interact with unverified contracts without undestanding the risks.