DeFi insurance pays buyers for specific onchain losses, such as a smart contract exploit, a stablecoin depeg or a custodian failure. This guide explains how cover pools work, how claims are decided, how pools price risk and stay solvent, and what to settle before building a DeFi insurance platform.
A pool of capital providers funds the cover and earns the premiums. The contracts are the simpler part of the product, while the harder parts are the definition of a valid claim, the pricing of risks with little history, and the solvency of the pool when a large protocol fails.
How DeFi insurance cover works
- Capital providers deposit assets into a pool and earn a share of the premiums, and the pool uses their capital to pay claims.
- A buyer chooses a covered protocol or event, an amount and a period, and pays a premium.
- An incident occurs, and the buyer files a claim with evidence of the loss.
- The claim is assessed by a vote, a committee or an automatic trigger.
- The pool pays approved claims, which reduces the balances of the capital providers.
DeFi insurance claims models
Discretionary mutual
Nexus Mutual is the best-known example, and its DAO runs as a discretionary mutual: members pool their funds, and the mutual decides each claim instead of paying it as a contractual right.
Membership requires an identity check with a government ID and a fee of 0.002 ETH, and the mutual does not accept members from a list of restricted countries. Nexus Mutual reports more than $18.5 million in claims paid as of August 2026.
The claims process changed in November 2025. Before that date NXM token stakers voted on claims, but a Claims Committee of three named expert assessors now decides each claim. The buyer posts a 0.05 ETH deposit, the vote lasts up to 72 hours, and two of the three assessors must accept the claim. A 24-hour cool-down follows, during which an Advisory Board can reverse a fraudulent vote.
Nexus Mutual chose the discretionary structure partly for legal reasons. A mutual that pays claims at its discretion is designed to sit outside the legal definition of insurance in the places it operates.
Parametric cover
A parametric product pays out automatically when a measurable condition occurs, such as a stablecoin trading below a set price for a set period. Payouts are fast, and nobody judges the claim.
The weakness is basis risk: the trigger may fire when the buyer had no loss, or it may fail to fire when the buyer had one. Etherisc publishes the Generic Insurance Framework, an open Solidity library for insurance products, and its documentation includes a depeg protection product.
Audit-linked cover
In this model, a security firm backs its audits with a cover pool, so the auditor loses capital if audited code is exploited. Every cover in the pool, however, depends on the work of that one audit firm. The model is rare today, and Sherlock, an audit firm known for this approach, now lists audits and bug bounties in its documentation but no cover product.
DeFi insurance models compared
| Model | Who decides the claim | Speed | Main weakness |
|---|---|---|---|
| Discretionary mutual with token voting | Members who stake tokens | Days to weeks | Voters are also capital providers, so they lose money when they accept a claim; cover terms can be unclear |
| Committee-assessed | Named expert assessors | About 3 days plus cool-down at Nexus Mutual | Central control, conflicts of interest |
| Parametric | An automatic trigger | Fast | Basis risk, oracle manipulation |
| Audit-linked | Contract terms with the auditor | Varies | Exposure concentrated in one firm |
Pricing and capital in a DeFi insurance platform
Smart contract failure has little actuarial history, and losses are correlated, because one exploit of a shared library or bridge can cause claims across many covered protocols at once. Most pools use five controls:
- Capacity limits per protocol, so one failure cannot drain the pool.
- Risk-based prices that use audit history, time live, value at risk, upgradeability, admin key setup and dependencies.
- Capital models that size the pool against plausible worst cases, not average losses.
- Withdrawal delays for capital providers, so they cannot leave as soon as an exploit becomes public.
- Reinsurance or backstops for rare, very large losses, where these are available.
A pool that earns yield on its capital takes extra risk. If the pool invests in the same protocols it covers, one exploit hits both the investment and the cover.
Smart contract parts
- Capital pool. The pool tracks each provider's share, often in an ERC-4626-style vault.
- Cover tokens. ERC-721 NFTs record the terms, amount and expiry of each cover, so wallets can display the cover. Some designs also let the holder transfer the cover to another wallet.
- Pricing module. Governance or a risk team sets the pricing parameters.
- Claims module. The module runs assessor votes, in which dishonest assessors lose part of their staked tokens, or reads oracle triggers.
- Governance and timelocks. Every parameter change waits in a timelock before it takes effect.
Most covered protocols are lending markets, DEXs and bridges, and the cover wording must describe how each of these protocol types can fail. The DeFi lending protocols guide covers liquidations, and the DeFi exchange development guide covers exchange settlement. The smart contract audit guide explains what audits catch and what they miss, and both affect the price of cover.
Legal structure of DeFi insurance
Almost every country requires a license to sell insurance. A regulator can treat unlicensed onchain cover as insurance, a derivative or a collective investment, depending on the structure of the product and the way it is marketed.
Many products use the words "cover" or "protection" for this reason, but the name does not decide the legal question. A team should settle the legal entity, the membership rules and the country restrictions with a lawyer before it writes contracts.
How to evaluate a DeFi insurance platform or build partner
- The team includes people with insurance or risk modeling experience, not only Solidity engineers.
- The team can show how its claims process would have decided past exploits.
- The design handles many claims at once, and it handles many capital providers who withdraw at the same time.
- Independent firms audited the previous contracts, and the reports are public.
Frequently asked questions
What is DeFi insurance?
DeFi insurance is cover bought onchain against losses such as smart contract exploits, depegs or custodian failures. A pool of capital providers pays the claims and earns the premiums.
What does DeFi cover usually exclude?
Common exclusions are losses from phishing, stolen private keys and price drops that no covered event caused. The cover wording lists the exact exclusions.
Is parametric cover better than claims voting?
Parametric cover is faster and less subjective, but the buyer carries basis risk. It suits events that can be measured cleanly onchain, such as a depeg.
Can a DeFi insurance pool go insolvent?
Yes, a pool becomes insolvent if claims exceed its capital. Capacity limits, cautious capital models and withdrawal delays reduce that risk but do not remove it.