Price Sources

This page describes recommended ways to obtain an accurate cUSD price (and similarly for stcUSD), plus how to derive pricing on-chain from the cUSD contract and the protocol oracle.

Contract addresses for Ethereum mainnet are listed in Addresses.

Why not use DEX / AMM pool prices?

Do not rely on on-chain DEX prices from venues such as Curve, Uniswap, or similar AMMs as your primary cUSD reference.

cUSD can be minted and redeemed 1:1 with USDC (and other whitelisted reserve assets at published rates). There is little economic reason for liquidity providers to maintain deep two-sided AMM liquidity when mint and redeem offer a direct, tight on/off-ramp. As a result, DEX pools are often shallow, and spot or TWAP prices there can be noisy, easy to move, or unrepresentative of the price implied by reserves and the protocol oracle. Prefer the feeds and oracle methods on this page instead.

Recommended: external feeds

RedStone (reserve oracle)

The RedStone feed used for cUSD reserve / fundamental pricing is the on-chain wrapper 0x9A5a3c3Ed0361505cC1D4e824B3854De5724434A (Etherscan). The same feed is documented in the RedStone app at https://app.redstone.finance/app/token/cUSD_FUNDAMENTAL/.

DefiLlama (Coins API)

DefiLlama exposes current prices via the Coins API. Endpoint documentation: https://api-docs.defillama.com/#tag/coins/get/prices/current/{coins}. Example for cUSD on Ethereum (checksum-insensitive in the path):

https://coins.llama.fi/prices/current/ethereum:0xcccc62962d17b8914c62d74ffb843d73b2a3cccc

For stcUSD, use the stcUSD token address on the same network, for example:

https://coins.llama.fi/prices/current/ethereum:0x88887be419578051ff9f4eb6c858a951921d8888

DefiLlama’s pegged-asset adapter for Cap cUSD (issued supply / peg logic) is https://github.com/DefiLlama/peggedassets-server/blob/master/src/adapters/peggedAssets/cap-cusd/index.ts.

On-chain

The patterns below use the cUSD token contract and the mainnet Oracle (see Addresses).

Backing balances per asset

Call cUSD.assets() to obtain the ordered list of backing assets, then for each asset call cUSD.totalSupply(asset) to read how much of that reserve token is held in the cUSD vault for that asset. Together, these balances describe the collateral side of the basket that backs outstanding cUSD.

Redemption weights (1 cUSD → each underlying)

Using the same asset ordering from cUSD.assets(), call cUSD.getRedeemAmount(1e18) with 1e18 wei of cUSD (18 decimals). The return values give the amounts of each underlying you would receive for that redemption path, which you can treat as the per-asset conversion from one full cUSD unit into the basket (subject to fees and current oracle pricing encoded in the call). Align each entry in the returned arrays with the corresponding index in assets().

Protocol oracle price

Query the deployed Oracle contract (0xcD7f45566bc0E7303fB92A93969BB4D3f6e662bb) with getPrice(cusd_address), where cusd_address is the cUSD token address. That is the same getPrice surface as in https://github.com/cap-labs-dev/cap-contracts/blob/main/contracts/interfaces/IPriceOracle.sol (IPriceOracle in cap-contracts):

function getPrice(address _asset) external view returns (uint256 price, uint256 lastUpdated);

For semantics (staleness, backup oracles, adapters), see Oracles.

Etherscan proxy API

When trading volume on secondary-market pairs is low, a robust approach for both cUSD and stcUSD is to read the protocol oracle directly—sometimes described as using a virtual price (the economically meaningful value from the Oracle rather than thin AMM liquidity).

getPrice(address _asset) returns two uint256 values: the price and lastUpdated (last update timestamp). The signature is specified in Cap’s IPriceOracle (getPrice).

Integrator note: If you only deploy a small utility contract that forwards getPrice but drops lastUpdated, consumers may still get a spot price, but historical pricing pipelines often need both fields (or an equivalent archive of oracle updates) to attribute values correctly in time. Where possible, decode the full ABI return from eth_call against the Oracle (or index oracle update events) instead of stripping the timestamp.

Example: eth_call via Etherscan API v2

These are illustrative module=proxy eth_call URLs for Ethereum mainnet (chainid=1). Replace YOURAPIKEY with a valid Etherscan API key.

cUSD (getPrice on the Oracle for the cUSD token address):

https://api.etherscan.io/v2/api?chainid=1&module=proxy&action=eth_call&to=0xcD7f45566bc0E7303fB92A93969BB4D3f6e662bb&data=0x41976e09000000000000000000000000cccc62962d17b8914c62d74ffb843d73b2a3cccc&tag=latest&apikey=YOURAPIKEY

stcUSD:

https://api.etherscan.io/v2/api?chainid=1&module=proxy&action=eth_call&to=0xcD7f45566bc0E7303fB92A93969BB4D3f6e662bb&data=0x41976e0900000000000000000000000088887be419578051ff9f4eb6c858a951921d8888&tag=latest&apikey=YOURAPIKEY

Example JSON-RPC style response (shape may vary slightly by client; result is the ABI-encoded return data):

{"jsonrpc":"2.0","id":1,"result":"0x0000000000000000000000000000000000000000000000000000000005f56ea50000000000000000000000000000000000000000000000000000000069ca971b"}

Decode as two 32-byte words: first word = price, second word = lastUpdated (Unix timestamp in seconds). Scaling and staleness rules for price follow the Oracle configuration described in Oracles.