How to create an NFT

To create an NFT you have to:

Upload the image to IPFS like Arweave
Upload the JSON metadata to Arweave or similar storage service.
Call metaplex to create an account for the NFT

Upload to Arweave

upload-to-arweave.ts

import fs from "node:fs";
import Arweave from "arweave";

(async () => {
  const arweave = Arweave.init({
    host: "localhost",
    port: 1984,
    protocol: "http",
    timeout: 20000,
    logging: false
  });

  const host = arweave.getConfig().api.host;
  const port = arweave.getConfig().api.port;
  const protocol = arweave.getConfig().api.protocol;

  // Upload image to Arweave
  const data = fs.readFileSync("./code/nfts/upload-arweave/lowres-dog.png");

  const transaction = await arweave.createTransaction({
    data: data
  });

  transaction.addTag("Content-Type", "image/png");

  // Instead of generating a new wallet, you can use an existing one from your file system
  // useful in production environments
  // const wallet = JSON.parse(fs.readFileSync("./code/nfts/upload-arweave/wallet.json", "utf-8"))
  const wallet = await arweave.wallets.generate();
  const address = await arweave.wallets.getAddress(wallet);
  console.log("address:", address);

  await arweave.api.get(`/mint/${encodeURI(addr)}/10000000000000000`);
  await arweave.transactions.sign(transaction, wallet);

  const response = await arweave.transactions.post(transaction);
  console.log(response);

  const id = transaction.id;
  const imageUrl = id ? `${protocol}://${host}:${port}/${id}` : null;
  console.log("imageUrl", imageUrl);

  // Upload metadata to Arweave

  const metadata = {
    name: "Custom NFT #1",
    symbol: "CNFT",
    description: "A description about my custom NFT #1",
    seller_fee_basis_points: 500,
    external_url: "https://www.customnft.com/",
    attributes: [
      {
        trait_type: "NFT type",
        value: "Custom"
      }
    ],
    collection: {
      name: "Test Collection",
      family: "Custom NFTs"
    },
    properties: {
      files: [
        {
          uri: imageUrl,
          type: "image/png"
        }
      ],
      category: "image",
      maxSupply: 0,
      creators: [
        {
          address: "CBBUMHRmbVUck99mTCip5sHP16kzGj3QTYB8K3XxwmQx",
          share: 100
        }
      ]
    },
    image: imageUrl
  };

  const metadataString = JSON.stringify(metadata);

  const metadataTransaction = await arweave.createTransaction({
    data: metadataString
  });

  metadataTransaction.addTag("Content-Type", "application/json");

  await arweave.transactions.sign(metadataTransaction, wallet);

  console.log("metadata txid", metadataTransaction.id);

  const txnResult = await arweave.transactions.post(metadataTransaction);

  console.log(txnResult);
})();

Mint the NFT

import { createUmi } from "@metaplex-foundation/umi-bundle-defaults";
import {
  generateSigner,
  percentAmount,
  keypairIdentity,
  createAmount
} from "@metaplex-foundation/umi";
import {
  createNft,
  fetchDigitalAsset,
  mplTokenMetadata
} from "@metaplex-foundation/mpl-token-metadata";
import bs58 from "bs58";

(async () => {
  try {
    console.log("Creating Umi instance...");
    const umi = createUmi("http://127.0.0.1:8899");

    const keypair = umi.eddsa.createKeypairFromSecretKey(
      bs58.decode(
        "588FU4PktJWfGfxtzpAAXywSNt74AvtroVzGfKkVN1LwRuvHwKGr851uH8czM5qm4iqLbs1kKoMKtMJG4ATR7Ld2"
      )
    );

    await umi.rpc.airdrop(keypair.publicKey, createAmount(1, "SOL", 9));

    // Use keypairIdentity to set the keypair as the signer
    const signer = keypairIdentity(keypair);
    umi.use(signer);
    umi.use(mplTokenMetadata());

    console.log("Keypair loaded. Public key:", keypair.publicKey);

    console.log("Generating new mint address...");
    const mint = generateSigner(umi);

    console.log("Creating NFT...");
    const { signature } = await createNft(umi, {
      mint,
      name: "My NFT",
      // Replace this with your Arweave metadata URI
      uri: "https://ffaaqinzhkt4ukhbohixfliubnvpjgyedi3f2iccrq4efh3s.arweave.net/KUAIIbk6p8oo4XHRcq0U__C2r0mwQaNl0gQow4Qp9yk",
      sellerFeeBasisPoints: percentAmount(0),
      creators: [
        {
          address: keypair.publicKey,
          share: 100,
          verified: true
        }
      ]
    }).sendAndConfirm(umi);

    console.log("NFT created successfully!");
    console.log("Mint address:", mint.publicKey);
    console.log("Transaction signature:", signature);

    console.log("Fetching digital asset...");
    const asset = await fetchDigitalAsset(umi, mint.publicKey);
    console.log("Digital Asset:", asset);
  } catch (error) {
    console.error("Error:", error);
    console.error("Stack trace:", error.stack);
  }
})();