What is ERC721 on Solana?
If you're coming from the EVM ecosystem, one thing you know well is ERC721. NFTs (non-fungible tokens) are at the heart of many blockchain applications, and ERC721 is one of the first standards developers learn when deploying NFT collections. On Solana, what is the ERC721 equivalent and how does it differ?
ERC721 sets a standard for Non-Fungible Tokens (NFTs), meaning each token is unique (in type and value) compared to another token. The ERC721 standard is utilized to represent individual tokens with distinct identifiers. Unlike ERC20 tokens, ERC721 tokens can possess unique characteristics and functions.
Le Token Program (plus les métadonnées)
Sur Solana, il n'existe pas de nouveau smart contract pour chaque collection de NFT. Au lieu de cela, les NFT sont créés sous un seul Token Program onchain, le même utilisé pour les jetons fongibles - simplement frappé avec une offre de 1. Pour stocker des détails supplémentaires sur les NFT (comme le nom, le symbole, l'URI de l'image, etc.), les développeurs utilisent le Metaplex Token Metadata Program.
Metaplex Metadata est un protocole et une plateforme open-source pour les NFT (Non-Fungible Tokens) et les actifs numériques. Construit sur la blockchain Solana, Metaplex facilite l'ajout de métadonnées supplémentaires aux jetons sur Solana.
Cela diffère d'Ethereum, où vous déployez généralement un nouveau contrat ERC721 pour chaque collection. Pourquoi existe-t-il un seul programme principal pour les NFT sur Solana ? Cela est dû au modèle de compte Solana, qui sépare l'état (les données) de la logique d'exécution (le programme). Parce que Solana réutilise le Token Program pour tous les jetons, vous n'avez pas besoin d'écrire et de déployer un nouveau contrat NFT - juste un nouveau mint account avec offre = 1.
NFTs Don't Have Contract Addresses, Only Mint Addresses
On Ethereum, each NFT collection is identified by its Contract Address, and each token has a unique tokenId within that contract. On Solana, each NFT is identified by a Mint Address. The difference is that you don't deploy a separate "NFT contract" - you just instruct the universal Token Program to create a new mint.
Because Solana's Token Program is universal, there's no concept of a unique "NFT contract address." Instead, each NFT is a special SPL token (supply of 1) with its own Mint Address.
If you want a "collection," you group multiple mint addresses together via a Collection Address in Metaplex, but each minted NFT is still just an SPL token with a unique Mint Address.
No Approval Flow Needed
On Ethereum, ERC721 often relies on approve or setApprovalForAll for external marketplaces or dApps to transfer your NFTs. On Solana, each NFT is stored in a user's ATA(Associated token account), and a single transaction can include any necessary steps. There's no separate approval flow - one atomic transaction can handle all instructions (e.g. transfer ownership, update metadata, etc.).
What Does A Solana Token Program Look Like?
A very rough translation of the Solana Token Program would look like this:
// SPDX-License-Identifier: MIT license
pragma solidity =0.8.28;
struct Mint {
uint8 decimals;
uint256 supply;
address mintAuthority;
address freezeAuthority;
address mintAddress;
}
struct TokenAccount {
address mintAddress;
address owner;
uint256 balance;
bool isFrozen;
}
struct Metadata {
string name;
string symbol;
string tokenURI;
}
contract Spl721 {
mapping(address => Mint) public mints;
mapping(address => TokenAccount) public tokenAccounts;
mapping(address => Metadata) public nftMetadata;
mapping(address => bool) public mintAddresses;
mapping(address => bool) public tokenAddresses;
function initializeMint(
uint8 decimals,
address mintAuthority,
address freezeAuthority,
address mintAddress
)
public
returns (Mint memory)
{
require(!mintAddresses[mintAddress], "Mint already exists");
mints[mintAddress] = Mint(decimals, 0, mintAuthority, freezeAuthority, mintAddress);
mintAddresses[mintAddress] = true;
return mints[mintAddress];
}
function setMetadata(
address mintAddress,
string memory name,
string memory symbol,
string memory tokenURI
)
public
{
require(mintAddresses[mintAddress], "Mint does not exist");
nftMetadata[mintAddress] = Metadata(name, symbol, tokenURI);
}
function mintNFT(address toMintTokens, address mintAddress) public {
require(mintAddresses[mintAddress], "NFT mint does not exist");
require(mints[mintAddress].mintAuthority == msg.sender, "Only the mint authority can mint");
require(mints[mintAddress].supply == 0, "NFT already minted");
mints[mintAddress].supply = 1;
address tokenAddress = address(uint160(uint256(keccak256(abi.encodePacked(toMintTokens, mintAddress)))));
if (!tokenAddresses[tokenAddress]) {
tokenAccounts[tokenAddress] = TokenAccount(mintAddress, toMintTokens, 0, false);
tokenAddresses[tokenAddress] = true;
}
tokenAccounts[tokenAddress].balance = 1;
tokenAccounts[tokenAddress].owner = toMintTokens;
}
function transfer(address to, address mintAddress, uint256 amount) public {
address toTokenAddress = address(uint160(uint256(keccak256(abi.encodePacked(to, mintAddress)))));
address fromTokenAddress = address(uint160(uint256(keccak256(abi.encodePacked(msg.sender, mintAddress)))));
require(tokenAccounts[fromTokenAddress].balance >= amount, "Insufficient balance");
require(amount == 1, "Only transferring 1 NFT at a time");
require(tokenAccounts[fromTokenAddress].owner == msg.sender, "Not the NFT owner");
require(!tokenAccounts[fromTokenAddress].isFrozen, "Sender token account is frozen");
if (tokenAddresses[toTokenAddress]) {
require(!tokenAccounts[toTokenAddress].isFrozen, "Receiver token account is frozen");
}
if (!tokenAddresses[toTokenAddress]) {
tokenAccounts[toTokenAddress] = TokenAccount(mintAddress, to, 0, false);
tokenAddresses[toTokenAddress] = true;
}
tokenAccounts[fromTokenAddress].balance -= amount;
tokenAccounts[toTokenAddress].balance += amount;
tokenAccounts[toTokenAddress].owner = to;
}
function freezeAccount(address owner, address mintAddress) public {
require(mintAddresses[mintAddress], "Mint does not exist");
require(mints[mintAddress].freezeAuthority == msg.sender, "Only the freeze authority can freeze");
address tokenAddress = address(uint160(uint256(keccak256(abi.encodePacked(owner, mintAddress)))));
require(tokenAddresses[tokenAddress], "Token account not found");
tokenAccounts[tokenAddress].isFrozen = true;
}
function getMint(address token) public view returns (Mint memory) {
return mints[token];
}
function getTokenAccount(address owner, address token) public view returns (TokenAccount memory) {
return tokenAccounts[address(uint160(uint256(keccak256(abi.encodePacked(owner, token)))))];
}
function getMetadata(address mintAddress) public view returns (Metadata memory) {
return nftMetadata[mintAddress];
}
}
As you can see in the contract, instead of an approval flow, there is only a transfer function to move tokens. On Solana, a single transaction can call multiple smart contract functions atomically, removing the need for the approval flow. Another difference is that everything is stored in a token account on Solana, keeping the details of the owner's tokens separate from the other state.
Where's the NFT Metadata?
On Ethereum, ERC721 contracts often store a metadata URI or embed logic for fetching token metadata. On Solana, the Token Metadata Program (by Metaplex) handles NFT metadata in a separate account. You can include fields like name, symbol, description, image URI, and more--all without changing the underlying Token Program. This does mean there's a separate instruction in your minting transaction to attach metadata. Since Solana can handle multiple program calls atomically in one transaction, you can easily create the mint and set up metadata in a single go.
Tradeoffs of Each Approach
Now that you have a general idea of how the token program and metadata program on Solana works, let's go through some of the tradeoffs of each NFT standard.
ERC721
- Highly customizable contracts
- New contract deployment for each collection
- Hard to index across many contracts
- Metadata often defined in contract or via URIs
- Requires individual audits
Solana NFT (SPL + Metaplex)
- Single program for all NFTs
- New NFTs created by transactions, not by new contracts
- Easier to index since there's one main program
- Metadata stored in a separate program
- Reuses existing audited code
High-Level Comparison
Below is a table comparing the basic steps of deploying an ERC-721 token on Ethereum vs. creating an NFT (SPL token with metadata) on Solana. (On Solana, you can freely mint SPL tokens by using the spl-token command in the command-line tool.)
| Étape | Ethereum (ERC-721) | Solana (SPL + Metaplex) |
|---|---|---|
| 1. Préparer le code du jeton | Utilisez généralement les bibliothèques ERC721 d'OpenZeppelin. Vous créez un fichier Solidity (par exemple MyNFT.sol). | Aucun contrat personnalisé n'est nécessaire pour les fonctionnalités NFT de base. Le Token Program est déjà déployé. Vous créez simplement un mint account (supply = 1). |
| 2. Compiler et déployer | Compilez et déployez avec Hardhat/Truffle (par exemple npx hardhat run deploy.js --network ...). | Utilisez une CLI (par exemple spl-token create-token --decimals 0) ou un outil SDK (comme Candy Machine de Metaplex). Aucun déploiement de contrat séparé n'est requis. |
| 3. Créer le NFT | Appelez la fonction mint() du contrat, qui attribue le NFT à une adresse et définit généralement les URI de métadonnées du jeton. Les frais de gaz peuvent varier. | Exécutez spl-token mint <MINT_ADDRESS> 1 ou utilisez les instructions de frappe de Metaplex pour créer exactement 1 supply. Les frais de transaction sur Solana sont généralement très faibles. |
| 4. Créer un destinataire | Généralement juste une adresse Ethereum normale. Les utilisateurs doivent ajouter l'adresse du contrat NFT dans de nombreux portefeuilles pour le voir. | Chaque utilisateur possède un associated token account (ATA). Les portefeuilles comme Phantom reconnaissent automatiquement les ATA pour les NFT. Aucune étape supplémentaire pour « ajouter » le jeton, bien qu'il puisse apparaître sous un onglet « Objets de collection » une fois reconnu. |
| 5. Vérifier les résultats | Consultez sur Etherscan ou utilisez une marketplace NFT comme OpenSea. Souvent, les utilisateurs doivent ajouter manuellement l'adresse du contrat pour voir les jetons dans certains portefeuilles. | Utilisez solana balance <ADDRESS> ou spl-token accounts pour voir les avoirs en jetons. Vous pouvez également utiliser un explorateur Solana ou une marketplace NFT (Magic Eden, OpenSea Solana, etc.) pour confirmer la présence du NFT. |
| 6. Identifiants uniques | Adresse du contrat + tokenId. | Adresse de frappe (mint address). Chaque NFT est simplement un jeton SPL avec supply=1. |
| 7. Collections | Tous les jetons dans un contrat représentent généralement une seule collection. | Les collections sont attribuées via une « adresse de collection » dans Metaplex. Vous ne déployez pas de contrat dédié. |
| 8. Mises à jour du code | Pour les mises à niveau majeures, vous pouvez utiliser un modèle de proxy ou redéployer le contrat. Seuls les développeurs avancés le font généralement. | Le Token Program est fixe. Si vous avez besoin de fonctionnalités avancées (royalties, métadonnées dynamiques, etc.), vous pouvez utiliser ou créer des programmes onchain séparés. Metaplex prend également en charge les extensions comme les NFT programmables. |
| 9. Exigences d'audit | Chaque contrat nécessite généralement un audit, surtout si vous ajoutez une logique de frappe personnalisée, une marketplace, etc. | Le Token Program principal et le Metaplex Metadata Program ont été audités plusieurs fois. Pour une frappe standard d'un NFT, aucun audit de contrat supplémentaire n'est généralement nécessaire. |
Want to mint your own NFT on Solana? Check out this guide!
How to do ERC721 on Solana
Let's explore how to interact with the Token Program using solana/web3.js based on Ethereum's ERC721 interface structure.
As mentioned above, since NFT Collections on Solana are not tied to a specific contract, the concept of a tokenId does not exist. Therefore, to find the specific data of a token, you should use Mint Address or Collection Address.
How to do name()
function name() external view returns (string); // Returns the token collection nameYou can use @metaplex-foundation/umi-bundle-defaults and @metaplex-foundation/mpl-token-metadata to fetch and parse an NFT's off-chain metadata from its mint address.
import { createUmi } from "@metaplex-foundation/umi-bundle-defaults";
import { fetchDigitalAsset, mplTokenMetadata } from "@metaplex-foundation/mpl-token-metadata";
import { PublicKey } from "@metaplex-foundation/js";
const mintAddress = new PublicKey("Token Address");
async function name() {
try {
const umi = createUmi("https://api.devnet.solana.com");
umi.use(mplTokenMetadata());
const digitalAsset = await fetchDigitalAsset(umi, mintAddress);
return digitalAsset.metadata.name;
} catch (error) {
console.error("Error fetching NFT name:", error);
return null;
}
}
name().then(nftName => {
console.log("NFT Name:", nftName);
})
.catch(error => {
console.error("Error:", error);
});
How to do symbol()
function symbol() external view returns (string); // Returns the token collection symbolYou can also retrieve the symbol in the same way as name(), using @metaplex-foundation/umi-bundle-defaults and @metaplex-foundation/mpl-token-metadata.
import { createUmi } from "@metaplex-foundation/umi-bundle-defaults";
import { fetchDigitalAsset, mplTokenMetadata } from "@metaplex-foundation/mpl-token-metadata";
import { PublicKey } from "@metaplex-foundation/js";
const mintAddress = new PublicKey("Token Address");
async function symbol() {
try {
const umi = createUmi("https://api.devnet.solana.com");
umi.use(mplTokenMetadata());
const digitalAsset = await fetchDigitalAsset(umi, mintAddress);
return digitalAsset.metadata.symbol;
} catch (error) {
console.error("Error fetching NFT symbol:", error);
return null;
}
}
symbol().then(nftSymbol => {
console.log("NFT Symbol:", nftSymbol);
}).catch(error => {
console.error("Error:", error);
});
How to do tokenURI()
function tokenURI(uint256 _tokenId) external view returns (string); // Returns the tokenURI of the tokenYou can also retrieve the symbol in the same way as name(), using @metaplex-foundation/umi-bundle-defaults and @metaplex-foundation/mpl-token-metadata.
import { createUmi } from "@metaplex-foundation/umi-bundle-defaults";
import { fetchDigitalAsset, mplTokenMetadata } from "@metaplex-foundation/mpl-token-metadata";
import { PublicKey } from "@metaplex-foundation/js";
const mintAddress = new PublicKey("Token Address");
async function tokenURI( /* no tokenId */ ) {
try {
const umi = createUmi("https://api.devnet.solana.com");
umi.use(mplTokenMetadata());
const digitalAsset = await fetchDigitalAsset(umi, mintAddress);
return digitalAsset.metadata.uri;
} catch (error) {
console.error("Error fetching token URI:", error);
return null;
}
}
tokenURI()
.then(uri => {
console.log("Token URI:", uri);
})
.catch(error => {
console.error("Error:", error);
});
How to do ownerOf()
function ownerOf(uint256 _tokenId) public view returns (address) // Returns the owner of the tokenId tokenWe can check the owner of an NFT using the mint address instead of the tokenId.
import { Connection, PublicKey } from "@solana/web3.js";
const connection = new Connection("https://api.devnet.solana.com", "confirmed");
const mintAddress = new PublicKey("Token Address");
async function ownerOf( /*no tokenId*/ ){
const largestAccounts = await connection.getTokenLargestAccounts(new PublicKey(mintAddress));
const largestAccountInfo = await connection.getParsedAccountInfo(largestAccounts.value[0].address);
return largestAccountInfo.value.data.parsed.info.owner;
}
ownerOf().then(owner => {
console.log(owner);
}).catch(error => {
console.error("Error:", error);
});
How to do transferFrom()
function transferFrom(address _from, address _to, uint256 _tokenId) external payable; // Transfers tokenId token from _from to _toFirst, Let's look at this code for understanding logic:
On Solana, each token is identified by its unique Mint address, and users store their balances in an Associated Token Account (ATA). In a transaction, the ATA address is used as the sender or receiver for transferring tokens. Unlike on Ethereum, where you directly call an ERC-20 contract, Solana handles token transfer logic through its native system program.
We can make a transaction's transfer instruction through createTransferCheckedInstruction and send it through sendTransaction from @solana/spl-token.
import { Keypair, Transaction, Connection, PublicKey } from "@solana/web3.js";
import { createTransferCheckedInstruction } from "@solana/spl-token";
const connection = new Connection("https://api.devnet.solana.com", "confirmed");
// Replace with your real private key (as a Uint8Array)
const ownerSecretkey = [];
const ownerPrivatekeypair = Keypair.fromSecretKey(new Uint8Array(ownerSecretkey));
const fromPublicKey = ownerPrivatekeypair.publicKey; // The sender's public key
const toPublicKey = new PublicKey("Receiver's Wallet Address");
const mintAddress = new PublicKey("Token Address");
// Pre-existing ATA addresses (for `_from` and `_to`)
const ownerTokenAccount = new PublicKey("Associated Token Account of _from");
const receiverTokenAccount = new PublicKey("Associated Token Account of _to");
// For an NFT, decimals = 0 and amount = 1
async function transferFrom(_from, _to) {
try {
const tx = new Transaction().add(
createTransferCheckedInstruction(
ownerTokenAccount, // _from's ATA
mintAddress,
receiverTokenAccount, // _to's ATA
ownerPrivatekeypair.publicKey, // Authority for `_from` (the private key must match this public key)
1, // amount = 1 NFT
0 // decimals = 0 for NFT
)
);
// Send transaction (simple version)
await connection.sendTransaction(tx, [ownerPrivatekeypair]);
return true;
} catch (error) {
console.error("Error in transferFrom:", error);
return false;
}
}
transferFrom(fromPublicKey, toPublicKey)
.then(result => {
console.log("transferFrom result:", result);
})
.catch(error => {
console.error("Error:", error);
});
How we can check receiverTokenAddress through receiverAddress? We can use getOrCreateAssociatedTokenAccount. It will retrieve the associated token account, or create it if it doesn't exist.
import { Keypair, Transaction, Connection, PublicKey } from "@solana/web3.js";
import { createTransferCheckedInstruction, getOrCreateAssociatedTokenAccount } from "@solana/spl-token";
const connection = new Connection("https://api.devnet.solana.com", "confirmed");
// Insert your private key as a Uint8Array
const ownerSecretkey = [];
const ownerPrivatekeypair = Keypair.fromSecretKey(new Uint8Array(ownerSecretkey));
const fromAddress = ownerPrivatekeypair.publicKey; // The sender's public key
const toAddress = new PublicKey("Receiver's Wallet Address");
const mintAddress = new PublicKey("Token Address");
// For an NFT: decimals = 0, amount = 1
async function transferFrom(_from, _to) {
try {
// Retrieve (or create if missing) the sender's ATA
const ownerTokenAccount = await getOrCreateAssociatedTokenAccount(
connection,
ownerPrivatekeypair, // Fee payer
mintAddress,
_from
);
// Retrieve (or create if missing) the receiver's ATA
const receiverTokenAccount = await getOrCreateAssociatedTokenAccount(
connection,
ownerPrivatekeypair, // Fee payer (use the receiver if needed)
mintAddress,
_to
);
// Create transaction with a transfer of 1 NFT (decimals=0)
const tx = new Transaction().add(
createTransferCheckedInstruction(
ownerTokenAccount.address,
mintAddress,
receiverTokenAccount.address,
ownerPrivatekeypair.publicKey,
1, // Always transfer exactly 1 (NFT)
0 // decimals = 0 for an NFT
)
);
// Send the transaction
await connection.sendTransaction(tx, [ownerPrivatekeypair]);
return true;
} catch (error) {
console.error("Error in transferFrom:", error);
return false;
}
}
transferFrom(fromAddress, toAddress)
.then(result => {
console.log("Transaction result:", result);
})
.catch(error => {
console.error("Error:", error);
});
Want to explore more features? Check out this guide!
