Solana: Anchor development

TLDR:

Anchor is the standard framework for building Solana programs. It handles account validation, serialization, and security checks through Rust macros.
anchor init scaffolds a full workspace: program source, tests, deployment config, and TypeScript types.
The #[program] macro defines instructions, #[derive(Accounts)] defines account validation, and #[account] defines on-chain state.
Anchor 1.0.0 (April 2026) ships breaking changes: @anchor-lang/core replaces @coral-xyz/anchor, Surfpool replaces solana-test-validator, and LiteSVM is the default test template.

Prerequisites

Install the following before starting. The guide targets Anchor 1.0.0.

Tool	Version	Install
Rust	1.89.0+	`curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \| sh`
Solana CLI	3.1.10+	`sh -c "\$(curl -sSfL https://release.anza.xyz/v3.1.10/install)"`
Anchor CLI	1.0.0	`cargo install avm --git https://github.com/solana-foundation/anchor --locked && avm install 1.0.0 && avm use 1.0.0`
Node.js	22+	nodejs.org
Yarn	1.22+	`npm install -g yarn`
Surfpool	1.1.2+	Installation instructions

Verify your setup:

anchor --version    # anchor-cli 1.0.0
solana --version    # solana-cli 3.1.x
rustc --version     # rustc 1.89.0+
surfpool --version  # surfpool 1.1.2+

Anchor 1.0.0 uses Surfpool instead of solana-test-validator for anchor test. If Surfpool is not installed, anchor test will fail with a connection error. If you cannot install Surfpool, use anchor test --validator legacy to fall back to solana-test-validator.

Anchor 1.0.0 no longer requires the Solana CLI to be on your PATH for most commands. The anchor CLI ships native implementations of balance, airdrop, address, and deploy. You still need the Solana CLI for operations like solana-keygen and solana program close.

Creating a project

Scaffold a new Anchor workspace:

anchor init my-counter
cd my-counter

This creates a modular project structure with separate files for instructions, state, constants, and errors. If you prefer everything in a single lib.rs, use --template single:

anchor init my-counter --template single

The modular template (default) is recommended for production programs. It scales better as your program grows.

Test templates

Anchor 1.0.0 generates a LiteSVM Rust test by default. You can pick a different template:

anchor init my-counter --test-template mocha    # TypeScript with Mocha
anchor init my-counter --test-template mollusk   # Mollusk test library

Project structure

After anchor init, the workspace looks like this:

my-counter/
├── programs/
│   └── my-counter/
│       ├── src/
│       │   ├── lib.rs              # Entry point, module declarations
│       │   ├── constants.rs        # Program constants
│       │   ├── error.rs            # Custom error codes
│       │   ├── instructions.rs     # Re-exports instruction modules
│       │   ├── instructions/
│       │   │   └── initialize.rs   # Instruction handler
│       │   └── state.rs            # Account state definitions
│       └── Cargo.toml
├── tests/
│   └── my-counter.ts               # Test file (or src/ for Rust tests)
├── target/
│   ├── deploy/                      # Compiled .so and keypair
│   ├── idl/                         # Generated IDL JSON
│   └── types/                       # Generated TypeScript types
├── Anchor.toml                      # Workspace configuration
├── Cargo.toml                       # Rust workspace manifest
├── rust-toolchain.toml              # Rust MSRV pinning
└── package.json

Key directories:

programs/ — your on-chain programs. A workspace can contain multiple programs.
target/deploy/ — the compiled program binary (.so file) and program keypair.
target/idl/ — the generated IDL JSON file that clients use to interact with your program.
target/types/ — TypeScript type definitions generated from the IDL.

Anchor.toml

The workspace configuration file controls which cluster you deploy to, which wallet signs transactions, and what scripts run during testing:

[toolchain]
package_manager = "yarn"

[features]
resolution = true
skip-lint = false

[programs.localnet]
my_counter = "YourProgramId111111111111111111111111111111"

[provider]
cluster = "localnet"
wallet = "~/.config/solana/id.json"

[scripts]
test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 \"tests/**/*.ts\""

[hooks]

You can optionally pin versions in the [toolchain] section:

[toolchain]
anchor_version = "1.0.0"
solana_version = "3.1.10"
package_manager = "yarn"

The [registry] section has been removed in Anchor 1.0.0. If you see it in older examples, delete it.

Program anatomy

An Anchor program is built around four macros. Here is a complete counter program that demonstrates all of them:

use anchor_lang::prelude::*;

declare_id!("Cntr1111111111111111111111111111111111111111");

#[program]
pub mod my_counter {
    use super::*;

    pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
        let counter = &mut ctx.accounts.counter;
        counter.count = 0;
        counter.authority = ctx.accounts.authority.key();
        msg!("Counter initialized by {}", counter.authority);
        Ok(())
    }

    pub fn increment(ctx: Context<Increment>) -> Result<()> {
        let counter = &mut ctx.accounts.counter;
        counter.count = counter.count.checked_add(1)
            .ok_or(ErrorCode::Overflow)?;
        msg!("Counter incremented to {}", counter.count);
        Ok(())
    }
}

#[derive(Accounts)]
pub struct Initialize<'info> {
    #[account(
        init,
        payer = authority,
        space = 8 + Counter::INIT_SPACE,
        seeds = [b"counter", authority.key().as_ref()],
        bump,
    )]
    pub counter: Account<'info, Counter>,
    #[account(mut)]
    pub authority: Signer<'info>,
    pub system_program: Program<'info, System>,
}

#[derive(Accounts)]
pub struct Increment<'info> {
    #[account(
        mut,
        seeds = [b"counter", authority.key().as_ref()],
        bump,
        has_one = authority,
    )]
    pub counter: Account<'info, Counter>,
    pub authority: Signer<'info>,
}

#[account]
#[derive(InitSpace)]
pub struct Counter {
    pub count: u64,
    pub authority: Pubkey,
}

#[error_code]
pub enum ErrorCode {
    #[msg("Counter overflow")]
    Overflow,
}

The sections below break down each macro.

declare_id!

Sets the program’s on-chain address. By default, this matches the public key from /target/deploy/my_counter-keypair.json.

declare_id!("Cntr1111111111111111111111111111111111111111");

If the keypair and source code fall out of sync (for example, after cloning a repo), run:

anchor keys sync

Anchor 1.0.0 checks that the declare_id! value matches the keypair file during anchor build. A mismatch produces a compile error. Use anchor build --ignore-keys to skip this check if needed.

#[program]

Defines the module containing your instruction handlers. Each public function in this module becomes a callable instruction:

#[program]
pub mod my_counter {
    use super::*;

    pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
        // instruction logic
        Ok(())
    }
}

Every handler receives a Context<T> as its first parameter, where T is the accounts struct. Additional parameters become the instruction arguments that clients pass in. The Context struct provides:

ctx.accounts — the validated accounts
ctx.program_id — the program’s public key
ctx.remaining_accounts — extra accounts not in the struct
ctx.bumps — PDA bump seeds found during validation

#[derive(Accounts)]

Defines which accounts an instruction requires and how to validate them. Each field specifies an account with its type and constraints:

#[derive(Accounts)]
pub struct Initialize<'info> {
    #[account(
        init,
        payer = authority,
        space = 8 + Counter::INIT_SPACE,
        seeds = [b"counter", authority.key().as_ref()],
        bump,
    )]
    pub counter: Account<'info, Counter>,
    #[account(mut)]
    pub authority: Signer<'info>,
    pub system_program: Program<'info, System>,
}

Anchor validates all constraints before executing the instruction handler. If any check fails, the instruction aborts with a descriptive error. Common account types:

Type	Purpose
`Account<'info, T>`	Deserialized account owned by this program
`Signer<'info>`	Must have signed the transaction
`SystemAccount<'info>`	Any system-owned account
`Program<'info, T>`	An executable program account
`UncheckedAccount<'info>`	No validation — use with explicit checks

#[account]

Defines the data layout for accounts your program creates. Anchor adds an 8-byte discriminator as a prefix to distinguish account types:

#[account]
#[derive(InitSpace)]
pub struct Counter {
    pub count: u64,       // 8 bytes
    pub authority: Pubkey, // 32 bytes
}

The discriminator is the first 8 bytes of SHA256("account:Counter"). It is automatically set during init and verified during deserialization.

Account constraints

Constraints are the core of Anchor’s security model. They go inside #[account(...)] attributes and tell Anchor what to validate before executing your instruction.

Initialization constraints

Create a new account and set its discriminator:

#[account(
    init,
    payer = authority,
    space = 8 + Counter::INIT_SPACE,
)]
pub counter: Account<'info, Counter>,

The init constraint requires:

payer — the account paying the rent
space — total bytes (8-byte discriminator + your data)

Use init_if_needed to create only if the account does not already exist. This requires the init-if-needed feature in your Cargo.toml:

[dependencies]
anchor-lang = { version = "1.0.0", features = ["init-if-needed"] }

PDA constraints

Validate that an account is a PDA derived from specific seeds:

#[account(
    seeds = [b"counter", authority.key().as_ref()],
    bump,
)]
pub counter: Account<'info, Counter>,

When combined with init, this creates the PDA account:

#[account(
    init,
    payer = authority,
    space = 8 + Counter::INIT_SPACE,
    seeds = [b"counter", authority.key().as_ref()],
    bump,
)]
pub counter: Account<'info, Counter>,

Anchor finds and stores the canonical bump automatically. Access it in your handler with ctx.bumps.counter.

Use fixed-length seeds or include a separator between variable-length seeds. Without this, seeds = [b"ab", b"cd"] and seeds = [b"abcd"] produce the same PDA, which can lead to seed collision vulnerabilities.

Mutability and ownership

#[account(mut)]                          // Account must be mutable
#[account(mut, has_one = authority)]      // Must be mutable AND counter.authority == authority.key()
#[account(owner = some_program.key())]   // Account owned by a specific program
#[account(close = destination)]          // Close account, send lamports to destination

Reallocation

Resize an existing account:

#[account(
    mut,
    realloc = 8 + NewLayout::INIT_SPACE,
    realloc::payer = authority,
    realloc::zero = false,
)]
pub data_account: Account<'info, NewLayout>,

SPL token constraints

Create or validate token accounts:

#[account(
    init,
    payer = authority,
    token::mint = mint,
    token::authority = authority,
)]
pub token_account: Account<'info, TokenAccount>,

#[account(
    init,
    payer = authority,
    mint::decimals = 6,
    mint::authority = authority,
)]
pub mint: Account<'info, Mint>,

Accessing instruction arguments in constraints

Use #[instruction(...)] to reference instruction arguments in your constraints:

#[derive(Accounts)]
#[instruction(title: String)]
pub struct CreatePost<'info> {
    #[account(
        init,
        payer = author,
        space = 8 + 32 + 4 + title.len(),
        seeds = [b"post", author.key().as_ref(), title.as_bytes()],
        bump,
    )]
    pub post: Account<'info, Post>,
    #[account(mut)]
    pub author: Signer<'info>,
    pub system_program: Program<'info, System>,
}

In Anchor 1.0.0, the compiler enforces that #[instruction(...)] argument types and order match the handler signature. Mismatches that were previously silent now produce errors.

Space calculation

Every account needs enough space for the 8-byte discriminator plus its data fields.

Type sizes

Type	Bytes
`bool`	1
`u8` / `i8`	1
`u16` / `i16`	2
`u32` / `i32`	4
`u64` / `i64`	8
`u128` / `i128`	16
`Pubkey`	32
`[T; N]`	`size(T) * N`
`Vec<T>`	`4 + (size(T) * max_elements)`
`String`	`4 + max_bytes`
`Option<T>`	`1 + size(T)`
`Enum`	`1 + largest_variant`

Manual calculation

#[account]
pub struct GameState {
    pub player: Pubkey,    // 32
    pub score: u64,        // 8
    pub level: u16,        // 2
    pub active: bool,      // 1
}

// Total: 8 (discriminator) + 32 + 8 + 2 + 1 = 51 bytes

Using InitSpace

The InitSpace derive macro calculates space automatically. Use #[max_len(...)] for dynamic types:

#[account]
#[derive(InitSpace)]
pub struct UserProfile {
    pub authority: Pubkey,
    #[max_len(50)]
    pub username: String,           // 4 + 50 = 54 bytes
    #[max_len(5, 50)]
    pub interests: Vec<String>,     // 4 + (5 * (4 + 50)) = 274 bytes
    pub points: u64,
}

// In the accounts struct:
#[account(init, payer = authority, space = 8 + UserProfile::INIT_SPACE)]
pub profile: Account<'info, UserProfile>,

The #[max_len(5, 50)] on Vec<String> means: up to 5 strings, each up to 50 bytes.

Building and the IDL

Build your program:

anchor build

This produces three outputs:

Program binary — target/deploy/my_counter.so — the compiled BPF bytecode.
IDL file — target/idl/my_counter.json — a JSON description of your program’s instructions, accounts, and types.
TypeScript types — target/types/my_counter.ts — type definitions generated from the IDL.

IDL structure

The IDL maps your Rust program to a format that clients can consume:

{
  "address": "Cntr1111111111111111111111111111111111111111",
  "metadata": {
    "name": "my_counter",
    "version": "0.1.0",
    "spec": "0.1.0"
  },
  "instructions": [
    {
      "name": "initialize",
      "discriminator": [175, 175, 109, 31, 13, 152, 155, 237],
      "accounts": [
        { "name": "counter", "writable": true, "pda": { ... } },
        { "name": "authority", "writable": true, "signer": true },
        { "name": "system_program", "address": "11111111111111111111111111111111" }
      ],
      "args": []
    }
  ],
  "accounts": [
    { "name": "Counter", "discriminator": [255, 176, 4, 245, ...] }
  ],
  "types": [
    { "name": "Counter", "type": { "kind": "struct", "fields": [...] } }
  ]
}

On-chain IDL via Program Metadata Program

Anchor 1.0.0 replaces the legacy IDL storage mechanism with the Program Metadata Program (PMP). When you run anchor program deploy, the IDL is uploaded automatically. To skip the upload:

anchor program deploy --no-idl

Testing

Anchor 1.0.0 defaults to LiteSVM for Rust-based testing. LiteSVM runs an in-process Solana VM—faster startup and teardown than solana-test-validator.

TypeScript tests

For TypeScript tests (generated with --test-template mocha), the test file uses @anchor-lang/core:

import * as anchor from "@anchor-lang/core";
import { Program } from "@anchor-lang/core";
import { MyCounter } from "../target/types/my_counter";
import { PublicKey } from "@solana/web3.js";
import assert from "assert";

describe("my-counter", () => {
  const provider = anchor.AnchorProvider.env();
  anchor.setProvider(provider);

  const program = anchor.workspace.myCounter as Program<MyCounter>;
  const wallet = provider.wallet as anchor.Wallet;

  it("initializes the counter", async () => {
    const [counterPda] = PublicKey.findProgramAddressSync(
      [Buffer.from("counter"), wallet.publicKey.toBuffer()],
      program.programId
    );

    const tx = await program.methods
      .initialize()
      .accounts({
        authority: wallet.publicKey,
      })
      .rpc();

    const counter = await program.account.counter.fetch(counterPda);
    assert.equal(counter.count.toNumber(), 0);
    assert.ok(counter.authority.equals(wallet.publicKey));
    console.log("Initialize tx:", tx);
  });

  it("increments the counter", async () => {
    const [counterPda] = PublicKey.findProgramAddressSync(
      [Buffer.from("counter"), wallet.publicKey.toBuffer()],
      program.programId
    );

    const tx = await program.methods
      .increment()
      .accounts({
        authority: wallet.publicKey,
      })
      .rpc();

    const counter = await program.account.counter.fetch(counterPda);
    assert.equal(counter.count.toNumber(), 1);
    console.log("Increment tx:", tx);
  });
});

Anchor 1.0.0 renamed the TypeScript package from @coral-xyz/anchor to @anchor-lang/core. All existing tutorials and Stack Overflow answers that show @coral-xyz/anchor need the import updated.

Running tests

Anchor 1.0.0 uses Surfpool as the default local validator for anchor test:

anchor test

This starts Surfpool, builds and deploys your program, runs the test suite, and shuts down the validator. To use the legacy solana-test-validator instead:

anchor test --validator legacy

To run tests against an already-running local validator:

anchor test --skip-local-validator

Deploying

Local deployment

Start a local validator and deploy:

solana-test-validator
# In a separate terminal:
anchor program deploy

If anchor program deploy fails with a 503 error on get_recommended_micro_lamport_fee, pass a manual compute unit price:

anchor program deploy --with-compute-unit-price 1

This is a known issue that affects some local RPC configurations.

Deploying to devnet

Set your cluster to devnet in Anchor.toml:

[provider]
cluster = "Devnet"
wallet = "~/.config/solana/id.json"

Fund your wallet:

solana airdrop 5 --url devnet

Build and deploy:

anchor build
anchor program deploy

anchor program deploy in 1.0.0 automatically uploads the IDL to the on-chain Program Metadata Program. The IDL becomes fetchable by any client using Program.fetchIdl.

Deploying to mainnet with Chainstack

Deploy a Solana node on Chainstack or use the Chainstack Solana endpoint.
Set your cluster to your Chainstack endpoint in Anchor.toml:

[provider]
cluster = "https://solana-mainnet.core.chainstack.com/YOUR_CHAINSTACK_KEY"
wallet = "~/.config/solana/id.json"

Build and deploy:

anchor build
anchor program deploy

Mainnet deployment requires real SOL. Verify your program thoroughly on devnet before deploying to mainnet.

Client interaction

The IDL enables typed client interactions. Anchor’s TypeScript client (in the @anchor-lang/core package) deserializes accounts and instruction arguments automatically.

Connecting to a program

import * as anchor from "@anchor-lang/core";
import { Program } from "@anchor-lang/core";
import { Connection, PublicKey, Keypair } from "@solana/web3.js";
import { MyCounter } from "../target/types/my_counter";
import idl from "../target/idl/my_counter.json";

const CHAINSTACK_ENDPOINT = "CHAINSTACK_NODE_URL";
const connection = new Connection(CHAINSTACK_ENDPOINT, "confirmed");

// Load your wallet keypair from a JSON file (must be funded)
import fs from "fs";
const secretKey = Uint8Array.from(
  JSON.parse(fs.readFileSync("/path/to/keypair.json", "utf-8"))
);
const wallet = new anchor.Wallet(Keypair.fromSecretKey(secretKey));
const provider = new anchor.AnchorProvider(connection, wallet, {
  commitment: "confirmed",
});

const program = new Program<MyCounter>(idl as MyCounter, provider);

The anchor.workspace object is only available inside anchor test. For standalone scripts and frontend code, load the IDL JSON file directly and instantiate the program with new Program(idl, provider).

Sending transactions

The wallet must be funded before sending transactions. On devnet, request an airdrop first:

// Initialize
const tx = await program.methods
  .initialize()
  .accounts({
    authority: wallet.publicKey,
  })
  .rpc();

console.log("Transaction signature:", tx);

Fetching accounts

const [counterPda] = PublicKey.findProgramAddressSync(
  [Buffer.from("counter"), wallet.publicKey.toBuffer()],
  program.programId
);

// Fetch a single account
const counter = await program.account.counter.fetch(counterPda);
console.log("Count:", counter.count.toNumber());
console.log("Authority:", counter.authority.toBase58());

// Fetch all counter accounts
const allCounters = await program.account.counter.all();
allCounters.forEach((item) => {
  console.log("Address:", item.publicKey.toBase58());
  console.log("Count:", item.account.count.toNumber());
});

// Fetch with filters
const myCounters = await program.account.counter.all([
  {
    memcmp: {
      offset: 16, // 8 discriminator + 8 count
      bytes: wallet.publicKey.toBase58(),
    },
  },
]);

Listening to events

If your program emits events with the emit! macro:

#[event]
pub struct CounterIncremented {
    pub authority: Pubkey,
    pub new_count: u64,
}

// In your instruction handler:
emit!(CounterIncremented {
    authority: counter.authority,
    new_count: counter.count,
});

Subscribe from the client:

const listener = program.addEventListener("counterIncremented", (event) => {
  console.log("New count:", event.newCount.toNumber());
});

// Later, remove the listener:
program.removeEventListener(listener);

Common gotchas

CpiContext takes Pubkey, not AccountInfo

Anchor 1.0.0 removed the redundant AccountInfo copy from CpiContext. If you are adapting pre-1.0 code:

// Pre-1.0 (broken in 1.0.0)
CpiContext::new(
    ctx.accounts.token_program.to_account_info(),
    Transfer { ... }
)

// Anchor 1.0.0
CpiContext::new(
    ctx.accounts.token_program.key(),
    Transfer { ... }
)

Duplicate mutable accounts are now rejected

Passing the same mutable account twice in an instruction errors by default. If you intentionally need this, opt in with dup:

#[derive(Accounts)]
pub struct SwapAccounts<'info> {
    #[account(mut)]
    pub account_a: Account<'info, TokenAccount>,
    #[account(mut, dup)]
    pub account_b: Account<'info, TokenAccount>,
}

AccountInfo is deprecated in Accounts structs

Using AccountInfo directly inside #[derive(Accounts)] now produces a compile warning. Use UncheckedAccount instead:

// Deprecated
pub some_account: AccountInfo<'info>,

// Preferred
/// CHECK: Validated in instruction logic
pub some_account: UncheckedAccount<'info>,

Space must include the 8-byte discriminator

Every init constraint needs 8 extra bytes for the discriminator:

// Wrong — account will be too small
#[account(init, payer = user, space = Counter::INIT_SPACE)]

// Correct
#[account(init, payer = user, space = 8 + Counter::INIT_SPACE)]

Error codes are limited to one block

Anchor 1.0.0 restricts #[error_code] to a single definition per program. If you have multiple error blocks, consolidate them:

#[error_code]
pub enum ErrorCode {
    #[msg("Counter overflow")]
    Overflow,
    #[msg("Unauthorized")]
    Unauthorized,
    #[msg("Invalid input")]
    InvalidInput,
}

Surfpool vs solana-test-validator

anchor test now uses Surfpool by default. If you encounter compatibility issues:

# Fall back to the legacy validator
anchor test --validator legacy

Surfpool is faster but less feature-complete than solana-test-validator. Use the legacy validator when you need full RPC method support or when cloning accounts from mainnet.

Platform

Pricing

Core

Add-ons

Security

Web3 [de]coded

Subgraphs (Deprecated)

MCP servers

Marketplace

Chainstack Compare

Chainstack ChatGPT plugin

Chainstack DLP browser extension

Protocols

Advanced APIs

Tooling

​Prerequisites

​Creating a project

​Test templates

​Project structure

​Anchor.toml

​Program anatomy

​declare_id!

​#[program]

​#[derive(Accounts)]

​#[account]

​Account constraints

​Initialization constraints

​PDA constraints

​Mutability and ownership

​Reallocation

​SPL token constraints

​Accessing instruction arguments in constraints

​Space calculation

​Type sizes

​Manual calculation

​Using InitSpace

​Building and the IDL

​IDL structure

​On-chain IDL via Program Metadata Program

​Testing

​TypeScript tests

​Running tests

​Deploying

​Local deployment

​Deploying to devnet

​Deploying to mainnet with Chainstack

​Client interaction

​Connecting to a program

​Sending transactions

​Fetching accounts

​Listening to events

​Common gotchas

​CpiContext takes Pubkey, not AccountInfo

​Duplicate mutable accounts are now rejected

​AccountInfo is deprecated in Accounts structs

​Space must include the 8-byte discriminator

​Error codes are limited to one block

​Surfpool vs solana-test-validator

Prerequisites

Creating a project

Test templates

Project structure

Anchor.toml

Program anatomy

declare_id!

#[program]

#[derive(Accounts)]

#[account]

Account constraints

Initialization constraints

PDA constraints

Mutability and ownership

Reallocation

SPL token constraints

Accessing instruction arguments in constraints

Space calculation

Type sizes

Manual calculation

Using InitSpace

Building and the IDL

IDL structure

On-chain IDL via Program Metadata Program

Testing

TypeScript tests

Running tests

Deploying

Local deployment

Deploying to devnet

Deploying to mainnet with Chainstack

Client interaction

Connecting to a program

Sending transactions

Fetching accounts

Listening to events

Common gotchas

CpiContext takes Pubkey, not AccountInfo

Duplicate mutable accounts are now rejected

AccountInfo is deprecated in Accounts structs

Space must include the 8-byte discriminator

Error codes are limited to one block

Surfpool vs solana-test-validator