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Sky Savings allows apps to earn the Sky Savings Rate by depositing USDS into the sUSDS vault. The sUSDS vault follows the ERC-4626 standard — your app deposits USDS and receives sUSDS shares that automatically accrue yield.

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Resources

Sky Developer Docs

Official documentation for the Sky protocol and smart contracts.

Privy Wallets

Privy Wallets are a powerful tool for helping users interact with DeFi.

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Getting USDS

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Swap on a DEX

Your app can swap any supported token for USDS on any major decentralized exchange using a DEX aggregator or router.

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Convert DAI to USDS

On Ethereum, your app can convert DAI to USDS at a 1:1 rate through the DaiUsds converter contract. First, approve the converter to spend DAI, then call daiToUsds. 
import {encodeFunctionData, maxUint256, erc20Abi, parseUnits} from 'viem';
import {useSendTransaction} from '@privy-io/react-auth';

const {sendTransaction} = useSendTransaction();

const DAI_ADDRESS = '0x6B175474E89094C44Da98b954EedeAC495271d0F';
const DAI_USDS_CONVERTER = '0x3225737a9Bbb6473CB4a45b7244ACa2BEFdB276A';
const CHAIN_ID = 1; // Ethereum Mainnet

// Step 1: Approve the converter to spend DAI
const approveData = encodeFunctionData({
  abi: erc20Abi,
  functionName: 'approve',
  args: [DAI_USDS_CONVERTER as `0x${string}`, maxUint256]
});

await sendTransaction({
  to: DAI_ADDRESS as `0x${string}`,
  data: approveData,
  chainId: CHAIN_ID
});

// Step 2: Convert DAI to USDS
const converterAbi = [
  {
    type: 'function',
    name: 'daiToUsds',
    inputs: [
      {name: 'usr', type: 'address'},
      {name: 'wad', type: 'uint256'}
    ],
    outputs: [],
    stateMutability: 'nonpayable'
  }
] as const;
const amount = parseUnits('100', 18); // 100 DAI
const convertData = encodeFunctionData({
  abi: converterAbi,
  functionName: 'daiToUsds',
  args: [address, amount]
});

await sendTransaction({
  to: DAI_USDS_CONVERTER as `0x${string}`,
  data: convertData,
  chainId: CHAIN_ID
});

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Using Sky Savings with Privy

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Deposit USDS into Sky Savings

1

1. Configure addresses

Set up the sUSDS vault and USDS token addresses. The example below uses Ethereum Mainnet:
const SUSDS_VAULT_ADDRESS = '0xa3931d71877C0E7a3148CB7Eb4463524FEc27fbD';
const USDS_ADDRESS = '0xdC035D45d973E3EC169d2276DDab16f1e407384F';
const CHAIN_ID = 1; // Ethereum Mainnet
2

2. Approve the sUSDS vault to spend USDS

Use viem’s encodeFunctionData to encode the approval, and Privy’s useSendTransaction to send it:
import {encodeFunctionData, maxUint256, erc20Abi} from 'viem';
import {useSendTransaction} from '@privy-io/react-auth';

const {sendTransaction} = useSendTransaction();

const data = encodeFunctionData({
  abi: erc20Abi,
  functionName: 'approve',
  args: [SUSDS_VAULT_ADDRESS as `0x${string}`, maxUint256]
});

const tx = await sendTransaction({
  to: USDS_ADDRESS as `0x${string}`,
  data,
  chainId: CHAIN_ID
});
3

3. Deposit USDS into the vault

Use viem to encode the deposit and Privy’s useSendTransaction to fund the vault:
import {encodeFunctionData, parseUnits} from 'viem';
import {useSendTransaction} from '@privy-io/react-auth';

const {sendTransaction} = useSendTransaction();

const erc4626Abi = [
  {
    type: 'function',
    name: 'deposit',
    inputs: [
      {name: 'assets', type: 'uint256'},
      {name: 'receiver', type: 'address'}
    ],
    outputs: [{name: 'shares', type: 'uint256'}],
    stateMutability: 'nonpayable'
  }
] as const;
const depositAmount = parseUnits('100', 18); // 100 USDS (18 decimals)
const data = encodeFunctionData({
  abi: erc4626Abi,
  functionName: 'deposit',
  args: [depositAmount, address]
});

const tx = await sendTransaction({
  to: SUSDS_VAULT_ADDRESS as `0x${string}`,
  data,
  chainId: CHAIN_ID
});

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Check balance

Call the vault’s balanceOf function to get the user’s sUSDS shares, then call convertToAssets to see the current USDS value including accrued yield. 
import {publicClient} from './viem';

const erc4626Abi = [
  {
    type: 'function',
    name: 'balanceOf',
    inputs: [{name: 'account', type: 'address'}],
    outputs: [{name: '', type: 'uint256'}],
    stateMutability: 'view'
  },
  {
    type: 'function',
    name: 'convertToAssets',
    inputs: [{name: 'shares', type: 'uint256'}],
    outputs: [{name: '', type: 'uint256'}],
    stateMutability: 'view'
  }
] as const;

const userShares = await publicClient.readContract({
  address: SUSDS_VAULT_ADDRESS as `0x${string}`,
  abi: erc4626Abi,
  functionName: 'balanceOf',
  args: [address]
});

const usdsValue = await publicClient.readContract({
  address: SUSDS_VAULT_ADDRESS as `0x${string}`,
  abi: erc4626Abi,
  functionName: 'convertToAssets',
  args: [userShares]
});

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Withdraw from the vault

Your app can withdraw a specific amount of USDS or redeem all shares for a full exit. 
import {encodeFunctionData, parseUnits} from 'viem';
import {useSendTransaction} from '@privy-io/react-auth';

const {sendTransaction} = useSendTransaction();

const withdrawAbi = [
  {
    type: 'function',
    name: 'withdraw',
    inputs: [
      {name: 'assets', type: 'uint256'},
      {name: 'receiver', type: 'address'},
      {name: 'owner', type: 'address'}
    ],
    outputs: [{name: 'shares', type: 'uint256'}],
    stateMutability: 'nonpayable'
  }
] as const;
const withdrawAmount = parseUnits('50', 18); // 50 USDS
const data = encodeFunctionData({
  abi: withdrawAbi,
  functionName: 'withdraw',
  args: [withdrawAmount, address, address]
});
const tx = await sendTransaction({
  to: SUSDS_VAULT_ADDRESS as `0x${string}`,
  data,
  chainId: CHAIN_ID
});

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Key integration tips

  1. Always approve first: Your app must grant ERC-20 approval to the sUSDS vault before any deposit.
  2. USDS uses 18 decimals: Unlike USDC (6 decimals), USDS uses 18 decimals — use parseUnits('100', 18) for amounts.
  3. Use convertToAssets for real-time balances: This ERC-4626 method converts sUSDS shares to their current USDS value, including accrued yield.
  4. Supported chains: Sky Savings supports Ethereum, Base, Arbitrum, OP Mainnet, and Unichain.

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Conclusion

Privy makes it straightforward to build secure, user-friendly access to Sky Savings. For advanced use cases, refer to the Sky Developer Docs, or reach out in Slack.
Your app is now ready to interact with Sky Savings using Privy embedded wallets!