Overview

Concrete Vaults are ERC-4626-compliant smart contracts that wrap underlying ERC20 assets (e.g., WBTC, USDC) into vault shares (ctAssets).

Developers can think of each vault as a yield wrapper — deposits are deployed into yield strategies (money markets, liquidity provision, restaking, etc.).

From an integration perspective, this means a user’s deposit always results in ERC20 shares (ctAssets) that represent their claim on the vault’s underlying and accrued yield.

Usage

Whether you’re using vanilla JS/TS, React hooks, or Wagmi integration, you interact with the same underlying vault abstraction.

The Concrete SDK provides:

• Query vault details — decimals, symbols, total assets, balances.
• Approvals — approve the vault to spend the underlying ERC20.
• Deposits & redemptions — mint and redeem shares.
• Preview conversions — estimate output before sending a transaction.
• Multi-chain support — works on Ethereum, Arbitrum, Berachain, Katana, Corn, Morph.

User Action	SDK Method	Result
Get vault details	vault.getVaultDetails()	Metadata: symbols, decimals, ERC20 instances
Check underlying balance	details.underlying.erc20.balanceOf(address)	User’s token balance
Approve deposit	details.underlying.erc20.approve(vaultAddr, amount)	Allow vault to spend
Preview conversion	vault.previewConversion(amount)	Estimate shares minted / tokens redeemed
Deposit	vault.deposit(amount)	underlying consumed, shares minted
Check share balance	vault.balanceOf(address)	User’s ctAsset balance
Redeem shares	vault.redeem(amount)	Shares burned, underlying returned

Vault = ERC20 + underlying ERC20

Every vault exposes two ERC20 layers (while still being ERC-4626 compliant):

1. Vault Shares (ctAssets)
   • The vault itself extends ERC20.
   • You can call balanceOf, approve, transfer, etc. on the shares.
2. underlying ERC20
   • Exposed via vault.getUnderlyingErc20().
   • Full ERC20 instance: approve, balanceOf, transfer, etc.

Example Flow:

User → approves underlying ERC20 → vault consumes underlying → mints ctAssets (shares) → user can redeem later.

Before writing code, it often helps to build a mental model of the flow by trying it out directly in the Concrete app:

• Earn page — deposit into a live vault, see shares minted.
• Earn docs — walkthrough of how vault deposits work at the user level.

Then, when you come back to the SDK, you’ll see the exact same steps expressed in code.

1. Check underlying balance

const details = await vault.getVaultDetails();
const balance = await details.underlying.erc20.balanceOf(user);
console.log("USDC balance:", balance.toString());

1. Approve vault to spend underlying

await details.underlying.erc20.approve(vault.getAddress(), amount);

1. Optionally preview deposit

const decimals = await vault.getUnderlyingDecimals();
const preview = await vault.previewConversion(1n * 10n ** BigInt(decimals));
console.log("Vault tokens (preview):", preview.vaultTokensReciving.toString());

1. Deposit into vault

const tx = await vault.deposit(amount);
await tx.wait();

1. Receive ctAssets (vault shares)

const shareBal = await vault.balanceOf(user);
console.log("Vault shares:", shareBal.toString());

1. Redeem back into underlying

const redeemTx = await vault.redeem(shareBal);
await redeemTx.wait();