Getting ABI from known contract address through ethers.js

Question

I'm not looking for pointers to etherscan or to remix so I can compile it myself. I want to know how to take a known contract address, and, through ethers.js natively get the full contract ABI.

Answer 1

Provided that your contract is verified, you can get the ABI using the Etherscan API like:

const contractAddress = "0xaa25DAc5505cbD5650554eb3fc2B4e084A2c18C6"

fetch(`https://api-sepolia.etherscan.io/api?module=contract&action=getabi&address=${contractAddress}`)
    .then(response => {
        if (!response.ok) {
            throw new Error('Network response was not ok ' + response.statusText);
        }
        return response.json();
    })
    .then(data => {
        if (data.status == "1")
            console.log(JSON.parse(data.result))

        else
            console.log(data.result); // Some error while fetching ABI like "Invalid Address format", etc.

    })
    .catch(error => {
        console.error('There has been a problem with your fetch operation:', error);
    });

OUTPUT

NOTE: In case of mainnet, you need to get the Etherscan API Key and pass the same in the url, like:

https://api.etherscan.io/api?module=contract&action=getabi&address=0xBB9bc244D798123fDe783fCc1C72d3Bb8C189413&apikey=YourApiKeyToken