Compound

Compound is an open-source decentralized lending protocol deployed on Ethereum in 2018. Users can deposit supported ERC-20 tokens into protocol-managed money markets to earn interest or borrow assets by over-collateralizing with approved tokens. Rates adjust algorithmically in real time according to each market’s utilization ratio—the share of supplied assets currently borrowed—eliminating the need for manual pricing or direct counterparty matching.

The protocol has evolved through several iterations. Early versions relied on a multi-asset pooling system where suppliers received cTokens as interest-bearing ERC-20 representations of their share in the pool. The current generation, Compound III (also known as Comet), employs a streamlined single-base-asset model per deployment, featuring one primary token available for borrowing and a distinct set of approved collateral assets for over-collateralization.

The main interactions are supplying and borrowing. Suppliers deposit supported ERC-20 assets into a market and earn interest as utilization by borrowers grows. Rising demand relative to supply increases the utilization rate, which automatically pushes interest rates higher—compensating suppliers for liquidity provision during peak periods and signaling borrowers to scale back when costs climb.

Borrowers post approved collateral and draw loans up to the limit set by each asset’s collateral factor, a governance-defined parameter indicating the borrowable fraction of its value. Positions nearing or exceeding this threshold become subject to liquidation by third-party actors through an on-chain mechanism designed to maintain protocol solvency.

Interest rates for supply and borrow are computed per market based on real-time utilization—the percentage of the supplied pool that is borrowed. Low utilization lowers rates to stimulate borrowing activity, while high utilization raises them to draw in more suppliers and prompt borrowers to reduce leverage. This fully on-chain, algorithmic process requires no centralized intervention to set or adjust rates.

Compound III (Comet) shifts from the original multi-asset pool by structuring each deployment around a single base asset for borrowing, paired with a separate whitelist of collateral tokens. Borrowers can supply approved collateral to borrow the base token but cannot borrow the collateral assets themselves, enabling clearer risk segmentation across independent markets with their own governance parameters.

The COMP governance token empowers holders to propose and vote on protocol changes such as interest rate models, collateral factors, asset listings, and contract upgrades. Proposals are executed on-chain after a voting period and timelock, ensuring all modifications are transparent, auditable, and require token-weighted majority approval without reliance on any privileged administrative keys.

All Compound smart contracts, including those for Compound III Comet, are open-source and hosted on GitHub under the compound-finance organization. This public codebase allows developers to review logic, integrate via the contract ABI, and build applications on the lending infrastructure, with the Comet repository serving as the authoritative reference for the current generation’s implementation.

Compound facilitates multiple DeFi activities: token holders supply idle assets to earn algorithmically set interest while retaining ownership; traders borrow stablecoins against held collateral (such as USDC against WETH) to unlock liquidity without selling positions; other protocols embed Compound contracts to add lending and borrowing capabilities; analysts and developers query the open contracts and public RPC endpoints for real-time supply, borrow, and utilization data; and COMP holders engage in on-chain governance to shape risk parameters and protocol evolution.

Developers access open-source contracts and documentation at docs.compound.finance. Integration with Compound III Comet occurs directly on-chain using the publicly available ABI from the GitHub repository at github.com/compound-finance/comet, which includes full source code and deployment details. The interface supports programmatic supply, borrowing, market state queries, and health monitoring. Since governance is entirely on-chain, all parameter updates are reflected in protocol state and can be tracked without depending on off-chain APIs.

Security resources are available at compound.finance/docs/security, outlining the protocol’s approach to smart contract protection and listing completed audits. An active bug bounty runs via Immunefi to encourage responsible disclosure. All contracts are open-source, supporting ongoing community review alongside formal audits. Users and integrators are advised to consult these materials, examine audit reports, and apply suitable risk controls when interacting with the lending protocol.

Compound stands as one of the earliest established DeFi lending protocols, featuring open-source code, algorithmic markets, and on-chain COMP governance on Ethereum since 2018. Compound III delivers a single-base-asset design that improves risk isolation over the prior multi-asset model and supports independent market deployments. Developers and users should examine the open Comet contracts, documentation, and security resources to determine suitability for their lending, borrowing, or integration needs.