What Is a Solana Program? How Smart Contracts Work on Solana

What Is a Solana Program? How Smart Contracts Work on Solana

If you've been exploring the Solana ecosystem, you've probably heard the term 'Solana Program' thrown around. But if you're coming from Ethereum, the terminology can be confusing. On Ethereum, we call them 'smart contracts.' On Solana, they're called 'programs,' and they work quite differently.

This guide explains what Solana programs are, how they differ from Ethereum smart contracts, how they're written and deployed, and how you can use tools like Solyzer to monitor on-chain program activity and interactions.

What Is a Solana Program?

A Solana program is a smart contract that runs on the Solana blockchain. It's a piece of code that executes transactions, manages data, and enforces business logic on-chain.

However, the key difference from Ethereum is architectural:

On Ethereum, smart contracts own their own state. The contract code and the contract state are tightly coupled in a single account.

On Solana, programs are stateless. A Solana program is just code that executes logic. The state (data) is stored separately in accounts, and the program reads and modifies those accounts. This separation of concerns is revolutionary.

Programs vs Smart Contracts: Key Differences

Ethereum Smart Contracts

• Code and state are bundled together in a single smart contract account
• When you call a function, the contract automatically accesses its own state
• Storage is expensive (32 KB costs a lot in gas fees)
• Less parallelizable (contracts compete for sequential execution)

Solana Programs

• Code is stored in a program account, state is stored in separate data accounts
• Programs are stateless and read-only (they can't modify themselves)
• Programs explicitly receive accounts they need to read or write to
• Storage is cheap (SOL rent model is more efficient than Ethereum gas)
• Highly parallelizable (multiple programs can run simultaneously if they don't touch the same accounts)

How Solana Programs Work

A Solana program execution follows this flow:

1. User submits a transaction with instructions that call a program
2. Validator receives the transaction and routes it to the appropriate program
3. Program executes the instruction and receives an array of accounts to read/write
4. Program validates inputs and the accounts
5. Program reads and modifies account data
6. Program returns success or error
7. Validator confirms the transaction on-chain

Key point: The program receives all required accounts explicitly. It's not magically looking up some global state. This makes it very fast.

Programming Languages for Solana Programs

Rust (Recommended)

Rust is the primary language for Solana programs because:

• High performance (compiled to native machine code)
• Memory safety without garbage collection
• Excellent tooling for blockchain development
• Large Solana developer ecosystem

Example of a minimal Solana program in Rust:

use solana_program::{
    account_info::AccountInfo,
    entrypoint,
    entrypoint::ProgramResult,
    pubkey::Pubkey,
};

entrypoint!(process_instruction);

pub fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult {
    // Program logic here
    Ok(())
}

C

C is also supported but less common. It's used for performance-critical programs.

Python & JavaScript

Not native to Solana. You can write off-chain clients in these languages (to call programs), but on-chain programs must be Rust or C.

Accounts: The Data Model

In Solana, everything is an account. There are two types:

Program Accounts

Accounts that store program code. These are read-only and immutable.

Data Accounts

Accounts that store data modified by programs. These can be owned by a program, and only that program can modify them.

When you call a Solana program, you pass in the accounts it needs:

Transaction {
  instructions: [
    {
      program_id: TokenProgramAddress,
      accounts: [
        { pubkey: UserWalletAddress, isSigner: true, isWritable: false },
        { pubkey: TokenAccountAddress, isSigner: false, isWritable: true },
        { pubkey: TokenMintAddress, isSigner: false, isWritable: false }
      ],
      data: [...]
    }
  ]
}

This is much more explicit than Ethereum, where the contract just assumes it knows where its state is.

How Programs Are Deployed

1. Write the Program

Developer writes code in Rust.

2. Compile to BPF

BPF stands for Berkeley Packet Filter, but on Solana it's a bytecode format. The Rust code compiles to a .so binary.

cargo build-bpf

3. Deploy to Blockchain

The developer uses the Solana CLI or SDK to deploy:

solana program deploy target/deploy/my_program.so

This creates a program account on-chain containing the compiled bytecode. A gas-like fee is paid (but Solana calls it a transaction fee, much cheaper).

4. Program Is Live

Once deployed, the program address (public key) is immutable. Anyone can call it by sending a transaction with instructions to that program.

Common Solana Programs

System Program

Handles basic account creation, transfers, and system operations.

Token Program (SPL)

Manages fungible and non-fungible tokens (similar to ERC-20 and ERC-721).

Metaplex

A protocol for creating, minting, and managing NFTs.

Raydium

An automated market maker (DEX) program. Anyone can swap tokens by calling Raydium's program with the appropriate accounts.

Magic Eden

An NFT marketplace program.

Program Execution Model: Parallel Processing

Solana's biggest innovation is parallel execution. Because programs are stateless and explicitly list accounts they need:

• If two transactions touch different accounts, they can run in parallel
• If two transactions touch the same account, they run sequentially

This is why Solana can handle thousands of transactions per second. Ethereum's sequential execution (one transaction at a time) is the bottleneck.

Rent Model: Cost of Storing Data

In Solana, accounts must maintain a minimum balance (rent). If your account balance drops below the rent-exempt amount, the account is deleted.

Rent exemption threshold is about 2 years of rent for an account holding data. For example:

• An empty account: ~0.00089 SOL
• A token account: ~0.00203 SOL
• A larger data account: varies based on size

This is more efficient than Ethereum's permanent gas fees for storage.

How to Monitor Solana Programs with Solyzer

Solyzer provides real-time on-chain data for Solana programs:

• Program interactions: See which programs are being called most frequently
• Transaction volume: Monitor program call volume over time
• Account changes: Track when program-owned accounts are modified
• TVL by program: For DeFi programs, see total value locked
• User activity: See active users interacting with programs

For example, you can track:

• Raydium swap volume in real-time
• Magic Eden NFT sales activity
• Token transfers via the Token Program
• Custom program usage for new projects

When evaluating a new Solana project, check Solyzer to see:

• Is the program actually being used?
• How many transactions per day?
• What's the trend (growing or declining)?
• How much TVL does it have?

This data-driven approach beats reading whitepapers.

Security Considerations

Because programs are stateless and require explicit account passing, security errors are common:

Common Vulnerabilities

Missing signer checks: Program doesn't verify that the transaction signer owns an account they're trying to modify.

Missing owner checks: Program doesn't verify that an account is actually owned by the program.

Integer overflow/underflow: Solana Rust doesn't have checked arithmetic by default, leading to bugs.

Account deserialization bugs: If the program incorrectly interprets account data, it can lead to fund theft.

Auditing

Before using a Solana program, check:

• Is it audited? (Look for audit reports)
• Is the source code open-source? (On GitHub)
• How many users does it have? (Solyzer data)
• How much TVL? (Solyzer data)
• Any reported exploits? (Twitter/docs)

Building Programs: Getting Started

If you want to write a Solana program:

1. Learn Rust (or use C, but Rust is recommended)
2. Install Solana CLI and development tools
3. Follow the Solana documentation or use frameworks like Anchor
4. Write your program, test it locally
5. Deploy to devnet first (Solana's testnet)
6. Get a security audit
7. Deploy to mainnet

Anchor is a framework that makes writing Solana programs much easier:

use anchor_lang::prelude::*;

#[program]
mod hello_world {
    use super::*;
    pub fn hello(ctx: Context<Hello>) -> ProgramResult {
        Ok(())
    }
}

#[derive(Accounts)]
pub struct Hello {}

Much cleaner than raw Solana program code.

Programs vs Programs as a Service (PaaS)

Some platforms offer programs as a service:

• You don't deploy your own program
• You use an existing program someone else deployed
• You pay a fee per transaction (often a percentage of the swap/trade)

This is how DEXs and NFT marketplaces work. Raydium deployed its program once, and millions of users call it.

Conclusion: Why Solana Programs Matter

Solana programs represent a different paradigm from Ethereum smart contracts. By separating code from state and making programs stateless, Solana achieves:

• Higher throughput (thousands of TPS)
• Cheaper execution (very low transaction fees)
• Parallel processing capability
• More explicit, clearer security model

Understanding Solana programs is essential for:

• Traders: Knowing which programs handle your trades
• Developers: Building on Solana
• Investors: Evaluating Solana projects

Use Solyzer to monitor program activity, track on-chain metrics, and make data-driven decisions about which Solana programs are worth using or investing in. Real usage data beats marketing claims.

Ready to dive deeper into Solana on-chain data? Visit Solyzer at solyzer.ai and start analyzing program activity, transaction flows, and user behavior with professional-grade analytics.