Writing to Network

In the previous section, you learned how to read data from the Solana network. Now you'll learn how to write data to it. Writing to the Solana network involves sending transactions that contain one or more instructions.

Programs (smart contract) define the business logic for what each instruction does. When you submit a transaction, the Solana runtime executes each instruction in sequence and atomically (meaning either all instructions succeed or the entire transaction fails).

This section covers the following examples:

Transferring SOL between accounts
Creating a new token

These examples show how to build and send transactions to invoke Solana programs. For more details, refer to the Transactions and Instructions and Fees on Solana pages.

Transfer SOL

In this example, you'll learn how to transfer SOL between two accounts.

On Solana, each account has a specific program as its owner. Only the program owner can deduct an account's SOL (lamport) balance.

The System Program is the owner for all "wallet" accounts. To transfer SOL, you must invoke the System Program's transfer instruction.

Transfer SOL

import {
  LAMPORTS_PER_SOL,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  Keypair,
  Connection
} from "@solana/web3.js";

const connection = new Connection("http://localhost:8899", "confirmed");

const sender = new Keypair();
const receiver = new Keypair();

const signature = await connection.requestAirdrop(
  sender.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

const transferInstruction = SystemProgram.transfer({
  fromPubkey: sender.publicKey,
  toPubkey: receiver.publicKey,
  lamports: 0.01 * LAMPORTS_PER_SOL
});

const transaction = new Transaction().add(transferInstruction);

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [sender]
);

console.log("Transaction Signature:", `${transactionSignature}`);

const senderBalance = await connection.getBalance(sender.publicKey);
const receiverBalance = await connection.getBalance(receiver.publicKey);

console.log("Sender Balance:", `${senderBalance}`);
console.log("Receiver Balance:", `${receiverBalance}`);

Console

Click to execute the code.

Transfer SOL

import {
  LAMPORTS_PER_SOL,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  Keypair,
  Connection
} from "@solana/web3.js";

const connection = new Connection("http://localhost:8899", "confirmed");

const sender = new Keypair();
const receiver = new Keypair();

const signature = await connection.requestAirdrop(
  sender.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

const transferInstruction = SystemProgram.transfer({
  fromPubkey: sender.publicKey,
  toPubkey: receiver.publicKey,
  lamports: 0.01 * LAMPORTS_PER_SOL
});

const transaction = new Transaction().add(transferInstruction);

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [sender]
);

console.log("Transaction Signature:", `${transactionSignature}`);

const senderBalance = await connection.getBalance(sender.publicKey);
const receiverBalance = await connection.getBalance(receiver.publicKey);

console.log("Sender Balance:", `${senderBalance}`);
console.log("Receiver Balance:", `${receiverBalance}`);

Console

Click to execute the code.

Create a Connection to handle sending transactions and fetching account data.

In this example, we're connecting to the local test validator which runs on localhost:8899.

Connection

const connection = new Connection("http://localhost:8899", "confirmed");

Generate new keypairs to use as the sender and receiver accounts.

A Keypair includes:

A public key which serves as the account address
A private key used for signing transactions

Generate Keypairs

const sender = new Keypair();
const receiver = new Keypair();

Before we can transfer SOL, the sender account needs to have some SOL balance.

On networks other than mainnet, you can use the requestAirdrop method to get SOL for testing.

Airdrop

const signature = await connection.requestAirdrop(
  sender.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

The SystemProgram.transfer() method creates an instruction that transfers SOL from the fromPubkey account to the toPubkey account for the specified lamports amount.

Transfer Instruction

const transferInstruction = SystemProgram.transfer({
  fromPubkey: sender.publicKey,
  toPubkey: receiver.publicKey,
  lamports: 0.01 * LAMPORTS_PER_SOL
});

Create a transaction and add the instruction to the transaction.

In this example, we're creating a transaction with a single instruction. However, you can add multiple instructions to a transaction.

Transaction

const transaction = new Transaction().add(transferInstruction);

Sign and send the transaction to the network.

The sender keypair is required in the signers array to authorize the transfer of SOL from their account.

Send Transaction

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [sender]
);

The transaction signature is a unique identifier that can be used to look up the transaction on Solana Explorer.

Create a Connection to handle sending transactions and fetching account data.

In this example, we're connecting to the local test validator which runs on localhost:8899.

Connection

const connection = new Connection("http://localhost:8899", "confirmed");

Generate new keypairs to use as the sender and receiver accounts.

A Keypair includes:

A public key which serves as the account address
A private key used for signing transactions

Generate Keypairs

const sender = new Keypair();
const receiver = new Keypair();

Before we can transfer SOL, the sender account needs to have some SOL balance.

On networks other than mainnet, you can use the requestAirdrop method to get SOL for testing.

Airdrop

const signature = await connection.requestAirdrop(
  sender.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

The SystemProgram.transfer() method creates an instruction that transfers SOL from the fromPubkey account to the toPubkey account for the specified lamports amount.

Transfer Instruction

const transferInstruction = SystemProgram.transfer({
  fromPubkey: sender.publicKey,
  toPubkey: receiver.publicKey,
  lamports: 0.01 * LAMPORTS_PER_SOL
});

Create a transaction and add the instruction to the transaction.

In this example, we're creating a transaction with a single instruction. However, you can add multiple instructions to a transaction.

Transaction

const transaction = new Transaction().add(transferInstruction);

Sign and send the transaction to the network.

The sender keypair is required in the signers array to authorize the transfer of SOL from their account.

Send Transaction

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [sender]
);

The transaction signature is a unique identifier that can be used to look up the transaction on Solana Explorer.

Transfer SOL

import {
  LAMPORTS_PER_SOL,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  Keypair,
  Connection
} from "@solana/web3.js";

const connection = new Connection("http://localhost:8899", "confirmed");

Create a Token

In this example, you'll learn how to create a new token on Solana using the Token Extensions Program. This requires two instructions:

Invoke the System Program to create a new account.
Invoke the Token Extensions Program to initialize that account as a Mint.

Create Mint Account

import {
  Connection,
  Keypair,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  LAMPORTS_PER_SOL
} from "@solana/web3.js";
import {
  MINT_SIZE,
  TOKEN_2022_PROGRAM_ID,
  createInitializeMint2Instruction,
  getMinimumBalanceForRentExemptMint,
  getMint
} from "@solana/spl-token";

const connection = new Connection("http://localhost:8899", "confirmed");

const wallet = new Keypair();
// Fund the wallet with SOL
const signature = await connection.requestAirdrop(
  wallet.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

// Generate keypair to use as address of mint account
const mint = new Keypair();

// Calculate lamports required for rent exemption
const rentExemptionLamports =
  await getMinimumBalanceForRentExemptMint(connection);

// Instruction to create new account with space for new mint account
const createAccountInstruction = SystemProgram.createAccount({
  fromPubkey: wallet.publicKey,
  newAccountPubkey: mint.publicKey,
  space: MINT_SIZE,
  lamports: rentExemptionLamports,
  programId: TOKEN_2022_PROGRAM_ID
});

// Instruction to initialize mint account
const initializeMintInstruction = createInitializeMint2Instruction(
  mint.publicKey,
  2, // decimals
  wallet.publicKey, // mint authority
  wallet.publicKey, // freeze authority
  TOKEN_2022_PROGRAM_ID
);

// Build transaction with instructions to create new account and initialize mint account
const transaction = new Transaction().add(
  createAccountInstruction,
  initializeMintInstruction
);

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [
    wallet, // payer
    mint // mint address keypair
  ]
);

console.log("Transaction Signature:", `${transactionSignature}`);

const mintData = await getMint(
  connection,
  mint.publicKey,
  "confirmed",
  TOKEN_2022_PROGRAM_ID
);
);

Console

Click to execute the code.

Create Mint Account

import {
  Connection,
  Keypair,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  LAMPORTS_PER_SOL
} from "@solana/web3.js";
import {
  MINT_SIZE,
  TOKEN_2022_PROGRAM_ID,
  createInitializeMint2Instruction,
  getMinimumBalanceForRentExemptMint,
  getMint
} from "@solana/spl-token";

const connection = new Connection("http://localhost:8899", "confirmed");

const wallet = new Keypair();
// Fund the wallet with SOL
const signature = await connection.requestAirdrop(
  wallet.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

// Generate keypair to use as address of mint account
const mint = new Keypair();

// Calculate lamports required for rent exemption
const rentExemptionLamports =
  await getMinimumBalanceForRentExemptMint(connection);

// Instruction to create new account with space for new mint account
const createAccountInstruction = SystemProgram.createAccount({
  fromPubkey: wallet.publicKey,
  newAccountPubkey: mint.publicKey,
  space: MINT_SIZE,
  lamports: rentExemptionLamports,
  programId: TOKEN_2022_PROGRAM_ID
});

// Instruction to initialize mint account
const initializeMintInstruction = createInitializeMint2Instruction(
  mint.publicKey,
  2, // decimals
  wallet.publicKey, // mint authority
  wallet.publicKey, // freeze authority
  TOKEN_2022_PROGRAM_ID
);

// Build transaction with instructions to create new account and initialize mint account
const transaction = new Transaction().add(
  createAccountInstruction,
  initializeMintInstruction
);

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [
    wallet, // payer
    mint // mint address keypair
  ]
);

console.log("Transaction Signature:", `${transactionSignature}`);

const mintData = await getMint(
  connection,
  mint.publicKey,
  "confirmed",
  TOKEN_2022_PROGRAM_ID
);
);

Console

Click to execute the code.

Creating a token on Solana requires using both the @solana/web3.js and @solana/spl-token libraries.

Create a connection
Generate a keypair to pay for the transaction
Request an airdrop to fund the keypair

Connection & Wallet Setup

const connection = new Connection("http://localhost:8899", "confirmed");

const wallet = new Keypair();
const signature = await connection.requestAirdrop(
  wallet.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

Generate a keypair for the mint account.

The public key for this keypair will be used as the address for the mint account.

Mint Keypair

const mint = new Keypair();

Calculate the minimum lamports required for a mint account.

The getMinimumBalanceForRentExemptMint function calculates exactly how much SOL (in lamports) must be allocated for the data on a mint account.

Rent Exemption

const rentExemptionLamports =
  await getMinimumBalanceForRentExemptMint(connection);

The first instruction invokes the System Program's createAccount instruction to:

Allocate the required bytes for storing mint data
Transfer lamports from the wallet to fund the new account
Assign ownership of the account to the Token Extensions program (TOKEN_2022_PROGRAM_ID)

Create Account Instruction

const createAccountInstruction = SystemProgram.createAccount({
  fromPubkey: wallet.publicKey,
  newAccountPubkey: mint.publicKey,
  space: MINT_SIZE,
  lamports: rentExemptionLamports,
  programId: TOKEN_2022_PROGRAM_ID
});

The second instruction invokes the Token Extensions Program's createInitializeMint2Instruction instruction to initialize the mint account with the following data:

2 decimals
Wallet as both mint authority and freeze authority

Initialize Mint Instruction

const initializeMintInstruction = createInitializeMint2Instruction(
  mint.publicKey,
  2,
  wallet.publicKey,
  wallet.publicKey,
  TOKEN_2022_PROGRAM_ID
);

Add both instructions to a single transaction.

By combining both instructions into a single transaction, you ensure that the account creation and initialization happen atomically. Either both instructions succeed, or neither does.

This approach is common when building more complex Solana transactions, as it guarantees that all instructions execute together.

Transaction

const transaction = new Transaction().add(
  createAccountInstruction,
  initializeMintInstruction
);

Sign and send the transaction. Two signatures are required:

Wallet signs as the payer for transaction fees and account creation
Mint signs to authorize the use of its address for the new account

Send Transaction

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [
    wallet,
    mint
  ]
);

The transaction signature returned can be used to inspect the transaction on Solana Explorer.

Creating a token on Solana requires using both the @solana/web3.js and @solana/spl-token libraries.

Create a connection
Generate a keypair to pay for the transaction
Request an airdrop to fund the keypair

Connection & Wallet Setup

const connection = new Connection("http://localhost:8899", "confirmed");

const wallet = new Keypair();
const signature = await connection.requestAirdrop(
  wallet.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

Generate a keypair for the mint account.

The public key for this keypair will be used as the address for the mint account.

Mint Keypair

const mint = new Keypair();

Calculate the minimum lamports required for a mint account.

The getMinimumBalanceForRentExemptMint function calculates exactly how much SOL (in lamports) must be allocated for the data on a mint account.

Rent Exemption

const rentExemptionLamports =
  await getMinimumBalanceForRentExemptMint(connection);

The first instruction invokes the System Program's createAccount instruction to:

Allocate the required bytes for storing mint data
Transfer lamports from the wallet to fund the new account
Assign ownership of the account to the Token Extensions program (TOKEN_2022_PROGRAM_ID)

Create Account Instruction

const createAccountInstruction = SystemProgram.createAccount({
  fromPubkey: wallet.publicKey,
  newAccountPubkey: mint.publicKey,
  space: MINT_SIZE,
  lamports: rentExemptionLamports,
  programId: TOKEN_2022_PROGRAM_ID
});

The second instruction invokes the Token Extensions Program's createInitializeMint2Instruction instruction to initialize the mint account with the following data:

2 decimals
Wallet as both mint authority and freeze authority

Initialize Mint Instruction

const initializeMintInstruction = createInitializeMint2Instruction(
  mint.publicKey,
  2,
  wallet.publicKey,
  wallet.publicKey,
  TOKEN_2022_PROGRAM_ID
);

Add both instructions to a single transaction.

By combining both instructions into a single transaction, you ensure that the account creation and initialization happen atomically. Either both instructions succeed, or neither does.

This approach is common when building more complex Solana transactions, as it guarantees that all instructions execute together.

Transaction

const transaction = new Transaction().add(
  createAccountInstruction,
  initializeMintInstruction
);

Sign and send the transaction. Two signatures are required:

Wallet signs as the payer for transaction fees and account creation
Mint signs to authorize the use of its address for the new account

Send Transaction

const transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [
    wallet,
    mint
  ]
);

The transaction signature returned can be used to inspect the transaction on Solana Explorer.

Create Mint Account

import {
  Connection,
  Keypair,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  LAMPORTS_PER_SOL
} from "@solana/web3.js";
import {
  MINT_SIZE,
  TOKEN_2022_PROGRAM_ID,
  createInitializeMint2Instruction,
  getMinimumBalanceForRentExemptMint,
  getMint
} from "@solana/spl-token";

const connection = new Connection("http://localhost:8899", "confirmed");

const wallet = new Keypair();
const signature = await connection.requestAirdrop(
  wallet.publicKey,
  LAMPORTS_PER_SOL
);
await connection.confirmTransaction(signature, "confirmed");

Writing to Network

Transfer SOL

Create a Token

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