Overview

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

Each vault behaves as a yield wrapper: deposits are deployed into yield strategies such as money markets, liquidity provision, or restaking.

From an integration perspective, 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 are using vanilla JS/TS, React hooks, or Wagmi integration, you interact with the same underlying vault abstraction. The SDK is built on viem. If you are upgrading from 1.x, see Migrating from 1.x.

The Concrete SDK provides:

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

User action	SDK method	Result
Get vault details	vault.getVaultDetails()	Metadata: symbols, decimals, underlying address
Check underlying balance	(await vault.getUnderlyingErc20()).balanceOf(address)	User's underlying token balance
Approve deposit	(await vault.getUnderlyingErc20()).approve(vaultAddr, amount)	Allow vault to spend the underlying
Preview conversion	vault.previewConversion(amount)	Estimate shares minted or 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
Read live APY	vault.getApyDetails()	Live and historical APY, TVL, and history series
Read the deposit cap	vault.getDepositLimits()	Deposit cap and minimum deposit (V2)
Read the withdrawal cooldown	vault.getDepositLockWithFeeHook()	Cooldown period and locked shares (V2)
Forecast a withdrawal	vault.getWithdrawalForecast({ account })	Estimated availability of Withdrawal Queue requests (V2)

Vault = ERC20 + underlying ERC20

Every vault exposes two ERC20 layers while staying ERC-4626 compliant:

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

Example flow

A user approves the underlying ERC20, the vault consumes the underlying and mints ctAssets (shares), and the user can redeem the shares later.

Before writing code, you can build a mental model of the flow by trying it directly in the Concrete app:

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

The SDK expresses the same steps in code:

1. Check underlying balance

const erc20 = await vault.getUnderlyingErc20();
const balance = await erc20.balanceOf(user);
console.log("Underlying balance:", balance.toString());

2. Approve vault to spend underlying

const erc20 = await vault.getUnderlyingErc20();
await (await erc20.approve(vault.getAddress(), amount)).wait();

3. Optionally preview deposit

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

4. Deposit into vault

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

5. Receive ctAssets (vault shares)

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

6. Redeem back into underlying

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