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 разработчиков 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.
Token Program (плюс метаданные)
В Solana не создаётся новый смарт-контракт для каждой NFT-коллекции. Вместо этого NFT создаются в рамках единой ончейн-программы Token Program, той же, что используется для взаимозаменяемых токенов — просто с количеством выпуска, равным 1. Для хранения дополнительных данных NFT (таких как имя, символ, URI изображения и т.д.) разработчики используют Metaplex Token Metadata Program.
Metaplex Metadata — это протокол и платформа с открытым исходным кодом для NFT (невзаимозаменяемых токенов) и цифровых активов. Построенный на блокчейне Solana, Metaplex облегчает добавление дополнительных метаданных к токенам в Solana.
Это отличается от Ethereum, где вы обычно развёртываете совершенно новый контракт ERC721 для каждой коллекции. Почему в Solana существует единая основная программа для NFT? Это связано с моделью аккаунтов Solana, которая разделяет состояние (данные) и логику выполнения (программу). Поскольку Solana повторно использует Token Program для всех токенов, вам не нужно писать и развёртывать новый NFT-контракт — достаточно создать новый mint account с количеством выпуска = 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, и многим другим--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 progra
- 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.)
| Шаг | Ethereum (ERC-721) | Solana (SPL + Metaplex) |
|---|---|---|
| 1. Подготовка кода токена | Обычно используются библиотеки ERC721 от OpenZeppelin. Вы создаёте файл Solidity (например, MyNFT.sol). | Для базовой функциональности NFT кастомный контракт не требуется. Token Program уже развёрнута. Вы просто создаёте mint account (с количеством = 1). |
| 2. Компиляция и развёртывание | Компилируйте и разверните с помощью Hardhat/Truffle (например, npx hardhat run deploy.js --network ...). | Используйте CLI (например, spl-token create-token --decimals 0) или инструмент SDK (например, Candy Machine от Metaplex). Отдельное развёртывание контракта не требуется. |
| 3. Минтинг NFT | Вызовите функцию контракта mint(), которая назначает NFT адресу и обычно устанавливает URI метаданных токена. Комиссия за газ может варьироваться. | Выполните spl-token mint <MINT_ADDRESS> 1 или используйте инструкции минтинга Metaplex для создания ровно 1 единицы. Комиссия за транзакции в Solana обычно очень низкая. |
| 4. Создание получателя | Обычно это просто обычный адрес Ethereum. Пользователи должны добавить адрес контракта NFT во многих кошельках, чтобы увидеть его. | У каждого пользователя есть associated token account (ATA). Кошельки, такие как Phantom, автоматически распознают ATA для NFT. Никаких дополнительных шагов для «добавления» токена не требуется, хотя он может появиться во вкладке «Коллекционные предметы» после распознавания. |
| 5. Проверка результатов | Просмотр в Etherscan или использование NFT-маркетплейса, такого как OpenSea. Часто пользователи вручную добавляют адрес контракта, чтобы увидеть токены в некоторых кошельках. | Используйте solana balance <ADDRESS> или spl-token accounts для просмотра холдингов токенов. Вы также можете использовать Solana Explorer или NFT-маркетплейс (Magic Eden, OpenSea Solana и т.д.) для подтверждения наличия NFT. |
| 6. Уникальные идентификаторы | Адрес контракта + tokenId. | Адрес минта. Каждый NFT — это просто SPL-токен с supply=1. |
| 7. Коллекции | Все токены в одном контракте обычно представляют одну коллекцию. | Коллекции назначаются через «адрес коллекции» в Metaplex. Вам не нужно развёртывать отдельный контракт. |
| 8. Обновления кода | Для крупных обновлений вы можете использовать шаблон прокси или повторно развернуть контракт. Обычно это делают только продвинутые разработчики. | Token Program зафиксирована. Если вам нужны расширенные функции (роялти, динамические метаданные и т.д.), вы можете использовать или создать отдельные ончейн-программы. Metaplex также поддерживает расширения, такие как программируемые NFT. |
| 9. Требования к аудиту | Каждый контракт обычно требует аудита, особенно если вы добавляете кастомную логику минтинга, маркетплейс и т.д. | Основная Token Program и Metaplex Metadata Program проходили аудит множество раз. Для стандартного минта NFT дополнительный аудит контракта обычно не требуется. |
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 пользователей 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!
