SPL Token Integration with Anchor

After PDAs, token integration is the next skill that unlocks real apps.

This lesson focuses on correct token account wiring and safe instruction constraints.

Core Accounts You Need To Know

Mint account: token definition (decimals, authorities)
Token account (ATA usually): balance holder for an owner + mint
Token program: SPL Token or Token-2022 program

Always be explicit about which token program you support. Do not assume legacy SPL token program only.

Anchor Example: Mint Tokens

mint tokens with anchor_spl

use anchor_spl::token_interface::{
    Mint, MintTo, TokenAccount, TokenInterface, mint_to,
};

#[derive(Accounts)]
pub struct MintRewards<'info> {
    #[account(mut)]
    pub authority: Signer<'info>,

    #[account(mut)]
    pub mint: InterfaceAccount<'info, Mint>,

    #[account(mut)]
    pub destination: InterfaceAccount<'info, TokenAccount>,

    pub token_program: Interface<'info, TokenInterface>,
}

pub fn mint_rewards(ctx: Context<MintRewards>, amount: u64) -> Result<()> {
    let cpi_accounts = MintTo {
        mint: ctx.accounts.mint.to_account_info(),
        to: ctx.accounts.destination.to_account_info(),
        authority: ctx.accounts.authority.to_account_info(),
    };

    let cpi_ctx = CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        cpi_accounts,
    );

    mint_to(cpi_ctx, amount)?;
    Ok(())
}

Transfer With Decimal Checks

Use checked transfer patterns to avoid decimal mismatch bugs.

use anchor_spl::token_interface::{TransferChecked, transfer_checked};

pub fn transfer_points(ctx: Context<TransferPoints>, amount: u64, decimals: u8) -> Result<()> {
    let cpi_accounts = TransferChecked {
        mint: ctx.accounts.mint.to_account_info(),
        from: ctx.accounts.from_ata.to_account_info(),
        to: ctx.accounts.to_ata.to_account_info(),
        authority: ctx.accounts.owner.to_account_info(),
    };

    let cpi_ctx = CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        cpi_accounts,
    );

    transfer_checked(cpi_ctx, amount, decimals)?;
    Ok(())
}

Token Integration Guardrails

Validate account mint matches your expected mint
Validate token account owner where required
Do not trust client-provided decimals blindly
Enforce authority checks before mint/burn flows

Suggested Test Cases

Mint succeeds with valid authority
Mint fails with wrong authority
Transfer fails when source mint mismatches
Transfer succeeds for correct token program

Solana-Dev Client Note

For new off-chain scripts, prefer @solana/kit for transaction construction and confirmation logic. If existing Anchor TS/web3 flows are already in place, isolate legacy types at adapter boundaries.

Try This Next

Add an instruction that mints a fixed daily reward per user.
Prevent double-claim with a PDA claim record.
Add tests for both SPL Token and Token-2022 if your app supports both.