Account Types

Q: What Anchor version does this site use?

0.32.1 for anchor-lang, Anchor CLI, and examples in this section.

Q: Do I need Solana CLI alongside Anchor?

Yes. Solana CLI 3.0.10 handles keypairs, airdrops, and solana program inspection.

Q: Where does the IDL live after build?

target/idl/.json in your workspace.

Q: How do I test without devnet?

Use anchor test with Surfpool 0.12.0 or LiteSVM 0.6.x in CI.

Q: What is the 8-byte prefix on account data?

Anchor account discriminator; do not strip it when sizing space.

Anchor account wrapper types encode common validation rules. Pick the strictest type that matches your threat model, then add attribute constraints for relationships.

Recipe

#[derive(Accounts)]
pub struct Example<'info> {
    pub payer: Signer<'info>,
    pub data: Account<'info, MyState>,
    pub sys: SystemAccount<'info>,
    pub token_prog: Program<'info, Token>,
    /// CHECK: validated in handler
    pub oracle: UncheckedAccount<'info>,
}

When to reach for this: You choose types for a new accounts struct field.

Working Example

#[derive(Accounts)]
pub struct Deposit<'info> {
    #[account(mut)]
    pub user: Signer<'info>,
    #[account(
        mut,
        associated_token::mint = mint,
        associated_token::authority = user,
    )]
    pub user_ata: Account<'info, TokenAccount>,
    pub mint: Account<'info, Mint>,
    pub token_program: Program<'info, Token>,
    pub associated_token_program: Program<'info, AssociatedToken>,
}

What this demonstrates:

Signer requires a transaction signature
Account<T> checks owner and deserializes with discriminator
Program<T> pins program IDs for CPI targets
UncheckedAccount skips automatic safety checks

Deep Dive

Type Reference

Type	Automatic checks
`Signer<'info>`	`is_signer`
`Account<'info, T>`	Owner, discriminator, deserialize `T`
`InterfaceAccount<'info, T>`	Token-2022 / interface owners
`Program<'info, T>`	Program ID for `T`
`SystemAccount<'info>`	System program owner
`UncheckedAccount<'info>`	None

Rust Notes

Use AccountLoader<'info, T> for zero-copy accounts and Interface<'info, T> for token interfaces in 0.32.

Gotchas

Account without mut on writable data - Serialize fails at end of instruction. Fix: Add mut when persisting changes.
Program field omitted - CPI fails with wrong program ID. Fix: Include explicit Program<Token> etc.
UncheckedAccount for user funds - Attacker substitutes accounts. Fix: Use typed accounts or strict constraints.
Wrong Account<T> for token-2022 - Owner check fails. Fix: Use InterfaceAccount with TokenInterface.
Signer for PDA authority - PDAs cannot sign as Signer. Fix: Use seeds + invoke_signed or CPI with_signer.

Alternatives

Alternative	Use When	Don't Use When
AccountLoader	Large zero-copy state	Small Borsh structs
InterfaceAccount	Token-2022 mints/ATAs	Legacy SPL only
remaining_accounts	Dynamic sets	Fixed instruction layout

FAQs

What Anchor version does this site use?

0.32.1 for anchor-lang, Anchor CLI, and examples in this section.

Do I need Solana CLI alongside Anchor?

Yes. Solana CLI 3.0.10 handles keypairs, airdrops, and solana program inspection.

Where does the IDL live after build?

target/idl/<program>.json in your workspace.

Can I mix UncheckedAccount with Signer?

Yes, but every unchecked field needs explicit constraints or handler checks.

How do I test without devnet?

Use anchor test with Surfpool 0.12.0 or LiteSVM 0.6.x in CI.

What is the 8-byte prefix on account data?

Anchor account discriminator; do not strip it when sizing space.

Should I commit generated IDL?

Yes, or publish on-chain IDL so clients have a canonical source.

How do I debug constraint failures?

Run with logs; Anchor prints constraint name and account index.

Does Anchor work on Agave 4.1.1?

Yes. This stack targets Agave validators with Solana CLI 3.0.10.

What should I read next in this section?

See sibling articles linked in Related for deeper account types topics.

The #[account] Constraints - attributes
Token & Associated Token Constraints - SPL helpers
Custom Account Types - manual traits

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Recipe

#[derive(Accounts)]
pub struct Example<'info> {
    pub payer: Signer<'info>,
    pub data: Account<'info, MyState>,
    pub sys: SystemAccount<'info>,
    pub token_prog: Program<'info, Token>,
    /// CHECK: validated in handler
    pub oracle: UncheckedAccount<'info>,
}

When to reach for this: You choose types for a new accounts struct field.

Working Example

#[derive(Accounts)]
pub struct Deposit<'info> {
    #[account(mut)]
    pub user: Signer<'info>,
    #[account(
        mut,
        associated_token::mint = mint,
        associated_token::authority = user,
    )]
    pub user_ata: Account<'info, TokenAccount>,
    pub mint: Account<'info, Mint>,
    pub token_program: Program<'info, Token>,
    pub associated_token_program: Program<'info, AssociatedToken>,
}

What this demonstrates:

Signer requires a transaction signature
Account<T> checks owner and deserializes with discriminator
Program<T> pins program IDs for CPI targets
UncheckedAccount skips automatic safety checks

Deep Dive

Type Reference

Type	Automatic checks
`Signer<'info>`	`is_signer`
`Account<'info, T>`	Owner, discriminator, deserialize `T`
`InterfaceAccount<'info, T>`	Token-2022 / interface owners
`Program<'info, T>`	Program ID for `T`
`SystemAccount<'info>`	System program owner
`UncheckedAccount<'info>`	None

Rust Notes

Use AccountLoader<'info, T> for zero-copy accounts and Interface<'info, T> for token interfaces in 0.32.

Gotchas

Account without mut on writable data - Serialize fails at end of instruction. Fix: Add mut when persisting changes.
Program field omitted - CPI fails with wrong program ID. Fix: Include explicit Program<Token> etc.
UncheckedAccount for user funds - Attacker substitutes accounts. Fix: Use typed accounts or strict constraints.
Wrong Account<T> for token-2022 - Owner check fails. Fix: Use InterfaceAccount with TokenInterface.
Signer for PDA authority - PDAs cannot sign as Signer. Fix: Use seeds + invoke_signed or CPI with_signer.

Alternatives

Alternative	Use When	Don't Use When
AccountLoader	Large zero-copy state	Small Borsh structs
InterfaceAccount	Token-2022 mints/ATAs	Legacy SPL only
remaining_accounts	Dynamic sets	Fixed instruction layout

FAQs

What Anchor version does this site use?

0.32.1 for anchor-lang, Anchor CLI, and examples in this section.

Do I need Solana CLI alongside Anchor?

Yes. Solana CLI 3.0.10 handles keypairs, airdrops, and solana program inspection.

Where does the IDL live after build?

target/idl/<program>.json in your workspace.

Can I mix UncheckedAccount with Signer?

Yes, but every unchecked field needs explicit constraints or handler checks.

How do I test without devnet?

Use anchor test with Surfpool 0.12.0 or LiteSVM 0.6.x in CI.

What is the 8-byte prefix on account data?

Anchor account discriminator; do not strip it when sizing space.

Should I commit generated IDL?

Yes, or publish on-chain IDL so clients have a canonical source.

How do I debug constraint failures?

Run with logs; Anchor prints constraint name and account index.

Does Anchor work on Agave 4.1.1?

Yes. This stack targets Agave validators with Solana CLI 3.0.10.

What should I read next in this section?

See sibling articles linked in Related for deeper account types topics.

The #[account] Constraints - attributes
Token & Associated Token Constraints - SPL helpers
Custom Account Types - manual traits

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Account Types

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Account Types