Your First Smart Contract in Solana

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Building your first smart contract on Solana is an exciting step into the world of high-performance blockchain development. Solana’s fast transaction speeds, low fees, and scalable architecture make it a compelling platform for developers looking to build decentralized applications (dApps) and on-chain programs. This guide walks you through the foundational concepts of Solana development, helps you deploy a simple "Hello World" smart contract, and provides insights into how state is managed on-chain.

Whether you're experienced in web2 or just getting started with blockchain, this walkthrough ensures a smooth onboarding experience using Rust for program logic and JavaScript/TypeScript for client interaction.

Understanding Solana Development Workflows

Solana supports two primary development workflows: smart contract (on-chain program) development and dApp (client-side) development. These workflows work together to create a complete decentralized application.

Smart Contract Development on Solana

Unlike Ethereum, where smart contracts are typically written in Solidity, Solana programs are primarily built using Rust, though C and C++ are also supported. These programs run in Solana’s runtime environment and are compiled to Berkeley Packet Filter (BPF) bytecode for execution.

Once deployed, these programs live permanently on the blockchain and can be invoked by any user or application that submits a valid transaction. Communication happens via the JSON RPC API, which allows external clients to send instructions and read program state.

dApp Development with Client SDKs

On the client side, dApp development closely resembles traditional web development. You use a client SDK—such as solana-web3.js—to connect to the Solana network, sign transactions, and interact with deployed programs.

Solana Labs provides official SDKs for multiple languages including:

This flexibility allows developers to build dApps in their preferred language while still leveraging the power of Solana’s on-chain programs.

👉 Get started building your first dApp today with powerful tools and resources.

Creating Your First Solana Smart Contract

Let’s walk through building a basic "Hello World" smart contract that maintains a counter of how many times it has been greeted.

Prerequisites

Before beginning, ensure your development environment includes:

For Windows users, we recommend using WSL (Windows Subsystem for Linux) for smoother toolchain integration.

Configure the Solana CLI

Set your local environment:

solana config set --url localhost

Generate a new keypair if this is your first time:

solana-keygen new

Launch a Local Solana Cluster

Start a local test validator to simulate the blockchain:

solana-test-validator
Note: You may need to perform system tuning for optimal performance. See Solana documentation for details.

Monitor transaction logs in real time:

solana logs

Install required npm packages:

npm install

Writing the On-Chain Program in Rust

Here’s the core logic of our "Hello World" program:

pub fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    _instruction_data: &[u8],
) -> ProgramResult {
    msg!("Hello World Rust program entrypoint");
    
    let accounts_iter = &mut accounts.iter();
    let account = next_account_info(accounts_iter)?;

    if account.owner != program_id {
        return Err(ProgramError::IncorrectProgramId);
    }

    let mut greeting_account = GreetingAccount::try_from_slice(&account.data.borrow())?;
    greeting_account.counter += 1;
    greeting_account.serialize(&mut &mut account.data.borrow_mut()[..])?;

    msg!("Greeted {} time(s)!", greeting_account.counter);
    Ok(())
}

This function:

How State Is Stored on Solana

Unlike Ethereum, where contracts store data internally, Solana uses external accounts to hold state. Each greeting counter is stored in a separate account, which the program modifies upon invocation. This design enables parallel processing and contributes to Solana’s high throughput.

Client-Side Interaction: Sending Transactions

The client handles communication between users and the on-chain program. It performs five key steps:

1. Connect to the Cluster

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

2. Set Up a Payer Account

Ensures there’s a funded account to cover transaction fees.

3. Verify Program Deployment

Checks whether the "Hello World" program is already deployed. If not, deployment must occur first.

4. Send a "Hello" Transaction

Constructs and sends an instruction to increment the counter:

const instruction = new TransactionInstruction({
    keys: [{ pubkey: greetedPubkey, isSigner: false, isWritable: true }],
    programId,
    data: Buffer.alloc(0),
});
await sendAndConfirmTransaction(connection, new Transaction().add(instruction), [payer]);

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5. Query Updated State

After each greeting, retrieve the current count:

const accountInfo = await connection.getAccountInfo(greetedPubkey);
const greeting = borsh.deserialize(GreetingSchema, GreetingAccount, accountInfo.data);
console.log(`${greetedPubkey} has been greeted ${greeting.counter} time(s)`);

Deploying and Running the Program

Build the Rust program:

npm run build:program-rust

Deploy it to your local cluster:

solana program deploy dist/program/helloworld.so

Run the client:

npm run start

You should see output like:

Saying hello to <public-key>
Greeted 1 time(s)!
<public-key> has been greeted 1 time(s)

Each subsequent run will increment the counter.

Core Keywords in Solana Development

To enhance search visibility and align with user intent, here are essential SEO keywords naturally integrated throughout:

These terms reflect common search queries from developers exploring blockchain development on Solana.

Frequently Asked Questions

What language are Solana smart contracts written in?

Most Solana programs are written in Rust due to its memory safety and performance. However, C and C++ are also supported through BPF compilation.

Do I need to learn Rust to build on Solana?

While not mandatory for basic dApp development, understanding Rust is essential if you want to write or audit on-chain programs.

How does Solana store smart contract state?

Solana stores state in separate accounts rather than within the program itself. Programs read from and write to these accounts, enabling efficient parallel execution.

Can I use JavaScript instead of Rust?

Yes! You can build full-featured dApps using JavaScript/TypeScript with solana-web3.js. However, only Rust/C/C++ can be used for writing on-chain programs.

What is the role of the JSON RPC API?

The JSON RPC API serves as the bridge between client applications and the Solana blockchain. It allows dApps to send transactions, query account data, and listen to events.

How do I test my Solana program before going live?

Use solana-test-validator for local testing. Once ready, deploy to devnet or testnet clusters for broader validation.

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Connecting to Public Clusters

Solana offers three main networks:

Switch clusters using:

solana config set --url devnet

Return to local testing with:

solana config set --url localhost

Next Steps: Expand Your Skills

To deepen your expertise, explore:

Understanding these advanced patterns will prepare you for real-world dApp development involving custom errors, secure account handling, and optimized serialization strategies.

By mastering both client and program sides of Solana development, you position yourself at the forefront of next-generation decentralized application innovation.