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.
برنامج الرموز (بالإضافة إلى البيانات الوصفية)
على سولانا، لا يوجد عقد ذكي جديد لكل مجموعة NFT. بدلاً من ذلك، يتم إنشاء الرموز غير القابلة للاستبدال تحت Token Program واحد على السلسلة، نفس البرنامج المستخدم للرموز القابلة للاستبدال - فقط يتم سكّها بعرض قدره 1. لتخزين تفاصيل إضافية للرموز غير القابلة للاستبدال (مثل الاسم، الرمز، عنوان URI للصورة، إلخ)، يستخدم المطورون برنامج البيانات الوصفية للرموز من Metaplex.
Metaplex Metadata هو بروتوكول ومنصة مفتوحة المصدر للرموز غير القابلة للاستبدال (NFTs) والأصول الرقمية. مبني على بلوكتشين سولانا، يسهّل Metaplex إضافة بيانات وصفية إضافية إلى الرموز على سولانا.
هذا يختلف عن إيثيريوم، حيث تقوم عادةً بنشر عقد ERC721 جديد تماماً لكل مجموعة. لماذا يوجد برنامج رئيسي واحد للرموز غير القابلة للاستبدال على سولانا؟ السبب هو نموذج حسابات سولانا، الذي يفصل الحالة (البيانات) عن منطق التنفيذ (البرنامج). نظراً لأن سولانا تعيد استخدام Token Program لجميع الرموز، فأنت لا تحتاج إلى كتابة ونشر عقد NFT جديد - فقط حساب سك جديد بعرض = 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.)
| الخطوة | إيثيريوم (ERC-721) | سولانا (SPL + Metaplex) |
|---|---|---|
| 1. إعداد كود الرمز | عادةً ما تُستخدم مكتبات ERC721 من OpenZeppelin. تقوم بإنشاء ملف Solidity (مثل MyNFT.sol). | لا حاجة لعقد مخصص لوظائف NFT الأساسية. برنامج الرموز منشور بالفعل. أنت فقط تقوم بإنشاء حساب سك (العرض = 1). |
| 2. الترجمة والنشر | الترجمة والنشر باستخدام Hardhat/Truffle (مثل npx hardhat run deploy.js --network ...). | استخدم واجهة سطر أوامر (مثل spl-token create-token --decimals 0) أو أداة SDK (مثل Candy Machine من Metaplex). لا يلزم نشر عقد منفصل. |
| 3. سك NFT | استدعِ دالة mint() في العقد، والتي تخصص NFT لعنوان معين وعادةً ما تحدد روابط بيانات الرمز الوصفية. رسوم الغاز قد تختلف. | نفذ spl-token mint <MINT_ADDRESS> 1 أو استخدم تعليمات السك من Metaplex لإنشاء عرض واحد بالضبط. رسوم المعاملات على سولانا منخفضة للغاية عادةً. |
| 4. إنشاء المستلم | عادةً ما يكون مجرد عنوان إيثيريوم عادي. يجب على المستخدمين إضافة عنوان عقد NFT في العديد من المحافظ لرؤيته. | كل مستخدم لديه حساب رمز مرتبط (ATA). المحافظ مثل Phantom تتعرف تلقائياً على ATAs الخاصة بـ NFTs. لا حاجة لخطوة إضافية "لإضافة" الرمز، على الرغم من أنه قد يظهر تحت علامة تبويب "المقتنيات" بمجرد التعرف عليه. |
| 5. التحقق من النتائج | اعرض على Etherscan أو استخدم سوق NFT مثل OpenSea. غالباً ما يضيف المستخدمون يدوياً عنوان العقد لرؤية الرموز في بعض المحافظ. | استخدم solana balance <ADDRESS> أو spl-token accounts لرؤية ممتلكات الرموز. يمكنك أيضاً استخدام مستكشف سولانا أو سوق NFT (Magic Eden، OpenSea سولانا، إلخ) لتأكيد وجود NFT. |
| 6. المعرفات الفريدة | عنوان العقد + tokenId. | عنوان السك. كل NFT هو ببساطة رمز SPL بـ supply=1. |
| 7. المجموعات | جميع الرموز في عقد واحد عادةً ما تمثل مجموعة واحدة. | يتم تعيين المجموعات عبر "عنوان المجموعة" في Metaplex. لا تحتاج لنشر عقد مخصص. |
| 8. تحديثات الكود | بالنسبة للترقيات الرئيسية، قد تستخدم نمط البروكسي أو تعيد نشر العقد. عادةً ما يفعل ذلك المطورون المتقدمون فقط. | برنامج الرموز ثابت. إذا كنت بحاجة إلى ميزات متقدمة (حقوق ملكية، بيانات وصفية ديناميكية، إلخ)، يمكنك استخدام أو بناء برامج منفصلة على السلسلة. يدعم Metaplex أيضاً امتدادات مثل NFTs القابلة للبرمجة. |
| 9. متطلبات التدقيق | كل عقد عادةً ما يتطلب تدقيقاً، خاصةً إذا أضفت منطق سك مخصص، أو سوق، إلخ. | برنامج الرموز الرئيسي وبرنامج بيانات Metaplex الوصفية تم تدقيقهما عدة مرات. بالنسبة لسك قياسي لـ NFT، عادةً لا يلزم تدقيق عقد إضافي. |
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!
