How to Create NFT Token-Gated Communities

Learn how to use the Alchemy NFT API to verify ownership of an NFT, or grab a complete ownership snapshot for a collection!

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Bored Ape #4560

One of the most powerful use cases for NFTs is community building. As projects like CityDAO, Nouns DAO, and Bored Ape Yacht Club have shown, holding an NFT means far more than owning an expensive profile picture—it means being a member of an organization with social, cultural, and often financial capabilities.

For NFT projects seeking to create communities around their NFTs, one important application is creating token-gated experiences—using the security and privacy of public blockchains to create exclusive experiences for their holders. Alchemy's NFT APIs make it fast and easy for developers to create token-gated experiences with just a few lines of code.

Verifying NFT Ownership

The key to creating a token-gated experience is to verify that a particular user holds a particular NFT. Imagine a simple case: we want to create a website accessible only to holders of Bored Apes. We don't care which Ape, as long as it's part of the collection. For this case, Alchemy provides the isHolderOfCollection endpoint (called checkNftOwnership in the SDK):

// Setup: npm install alchemy-sdk
import { Alchemy, Network } from "alchemy-sdk";

const config = {
  apiKey: "<-- ALCHEMY APP API KEY -->",
  network: Network.ETH_MAINNET,
};
const alchemy = new Alchemy(config);

const main = async () => {
  // Check if 0xshah.eth owns a Bored Ape.
  const nfts = await alchemy.nft.checkNftOwnership(
    "0xshah.eth",
    ["0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d"]
  );
  // Print NFTs
  console.log(nfts);
};

// Execute the code
const runMain = async () => {
  try {
    await main();
    process.exit(0);
  } catch (error) {
    console.log(error);
    process.exit(1);
  }
};
const wallet = "0x994b342Dd87fc825F66E51FfA3EF71aD818B6893"
const contractAddress = "0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d"
const response = await axios.get(
  `https://eth-mainnet.g.alchemy.com/nft/v2/${API_KEY}/isHolderOfCollection?wallet=${wallet}&contractAddress=${contractAddress}`);

Grabbing an ownership snapshot for a collection

Beyond verifying ownership for a single user, we might want to grab a full ownership snapshot. For example, suppose we wanted to airdrop a special Bored Ape Love Potion to all of our Bored Ape holders at midnight on Valentine's Day. We can use the getOwnersForCollection endpoint to grab a list of all addresses that hold a Bored Ape:

const contractAddress = "0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d"
const response = await axios.get(
  `https://eth-mainnet.g.alchemy.com/nft/v2/${API_KEY}/getOwnersForCollection?contractAddress=${contractAddress}`);

By default, this API just returns a list of addresses, without telling us which tokens they own, or how many. Suppose that we want to airdrop one Bored Ape Love Potion for each Bored Ape a user holders. To do this, we can use the withTokenBalances param to fetch the exact tokens owned by each address:

const contractAddress = "0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d"
const response = await axios.get(
  `https://eth-mainnet.g.alchemy.com/nft/v2/${API_KEY}/getOwnersForCollection?contractAddress=${contractAddress}&withTokenBalances=true`);

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