DeFi lending explained: how it works and how to use it safely

DeFi lending is what banking looks like when you replace the bank with a smart contract. Lenders deposit crypto into a pool; borrowers pledge other crypto as collateral and take loans from that pool; interest flows back to lenders automatically. The whole arrangement settles in seconds, no application, no underwriter, no manager. It also means the protocol — not a human — decides when to liquidate, freeze, or repay.

How does DeFi lending work?

Most DeFi lending sits in one of two patterns:

Money-market pools (Aave, Compound, Morpho)

1. Lenders deposit an asset (USDC, ETH, etc.) into a shared pool. They receive a yield-bearing receipt token (aUSDC, cUSDC, etc.).
2. Borrowers deposit collateral into the same protocol (often a different asset than what they want to borrow).
3. Borrowers borrow against the pool, up to a fraction of their collateral’s value (the loan-to-value).
4. Interest accrues continuously. The rate floats with utilization.
5. Liquidation engine watches every borrow. If a borrower’s collateral drops below the liquidation threshold, any liquidator can call a function to sell the collateral and repay the loan, taking a small bounty.

Peer-to-peer lending (Teller Protocol, NFTfi, others)

Loans are matched one-to-one between a specific lender and a specific borrower at a fixed rate and a fixed term. No pool, no utilization curve — just an order book. Best for fixed-rate certainty and for collateral that pools don’t list.

Why do rates change in DeFi lending?

Every pool has an interest-rate model — usually a curve that’s roughly linear up to a target utilization (say 80%), then steep above it. The model has three jobs:

• Reward lenders proportional to demand. More borrowing → higher rates.
• Discourage 100% utilization. If a pool runs out of supply, lenders can’t withdraw. The kink in the curve makes the last 20% of utilization expensive.
• Self-correct. High rates pull in new lenders and push borrowers to repay; low rates do the opposite.

What are the risks for lenders?

• Smart-contract risk. A bug, exploit, or upgrade gone wrong can drain a pool. Audits help; insurance products (Nexus Mutual, Sherlock) exist but are imperfect.
• Oracle risk. Lending pools price collateral using on-chain oracles. A manipulated or stale oracle can make undercollateralized loans look healthy until the pool takes a loss.
• Liquidity risk. If utilization spikes to ~100%, you may not be able to withdraw immediately. Funds aren’t lost — they’re just locked until borrowers repay.
• Governance risk. Protocols can change parameters — rate curves, supported assets, liquidation thresholds — through token-holder votes. Pay attention.

What are the risks for borrowers?

• Liquidation. The defining risk. Your collateral can be sold without warning if its price drops below the threshold.
• Rate spikes. A variable-rate loan can become uneconomic if utilization in the pool jumps.
• The other risks lenders face — smart-contract, oracle, governance — apply to borrowers’ collateral too.

Our dedicated crypto-backed loans guide walks through the borrower-side mechanics in depth.

How do I get started with DeFi lending?

1. Get a non-custodial wallet. See our wallet guide.
2. Fund it with stablecoins on a Layer-2. Base, Arbitrum, and Optimism keep gas low.
3. Pick a pool or an offer. Teller surfaces live lending opportunities and borrow offers from across protocols on the home tab.
4. Start small. Deposit or borrow a fraction of your stack to learn the UX. Scale once you’ve been through one full cycle.
5. Track your positions. Health factor / LTV / utilization are the numbers that matter — monitor them.

The short version

DeFi lending is open, fast, and global. The yield comes from real on-chain demand, not from a bank’s spread. The price is that nothing is forgiving — if the contract triggers a liquidation, there’s no one to call. Used carefully it’s one of the best tools in crypto; used recklessly it’s a fast way to lose a position.