The DeFi Lending Pool Liquidity Simulator
A DeFi lending pool sets interest rates using a simple formula and no human underwriter. Try a scenario, or drag the sliders yourself, to see how a pool's own rules can turn an ordinary spike in borrowing into a liquidity squeeze — and how a "decentralised" protocol still has a run risk that looks a lot like a bank's.
Depositors who lend their assets into the pool to earn yield.
Borrowers who post collateral and draw liquidity out of the pool.
Utilisation
60%
Borrow APR
7.2%
Supply APY
4.1%
Available to Withdraw
$4.0M
Comfortable buffer
Capital Flow
Depositors fund the pool; borrowers draw against it. Dot density and speed track how hard the pool is working.
The Interest Rate Curve
This is the entire "monetary policy" of the pool: a formula, not a committee. Rates rise gently until the kink point, then spike hard to push utilisation back down.
Pool Composition
Healthy pool
At 60% utilisation, the pool is comfortably below the kink point. Depositors can withdraw on demand, and the algorithm has no need to intervene.
What this is actually showing
No lender of last resort
In a bank run, a central bank can step in. In a DeFi pool, once utilisation hits 100%, the last depositor to try to withdraw simply cannot — the code has no more liquidity to give them, no matter what the interest rate says.
The rate spike is the alarm, not the fix
The kinked curve is designed to make borrowing expensive enough to push utilisation back down. It only works if borrowers respond fast enough — and in a genuine liquidity crunch, they often don't.
This is a systemic question, not a coding one
The mechanism is transparent and auditable; the risk it manages — a maturity and liquidity mismatch between depositors and borrowers — is the same risk regulators have supervised in banks for a century.
This explainer accompanies the blog post "Liquidity Is a Number Until It Isn't".