Proof of Reserves
Proof of reserves is evidence a crypto platform publishes to show that it holds enough assets to cover customer balances. A good one shows both what the platform owns and what it owes its customers; a weak one shows only half.
What a proof of reserves tries to show
When you leave coins on a centralized exchange or lending platform, you no longer hold them yourself. You hold a claim on the platform. A proof of reserves (PoR) is an attempt to show that those claims are backed, meaning the platform controls at least as many coins as its customers are owed.
The idea gained wide attention after FTX collapsed in November 2022, when it emerged that customer deposits had been used elsewhere and the exchange could not meet withdrawals. Several large exchanges began publishing reserve reports soon after.
How the check is done
The asset side is usually shown on-chain. The platform publishes wallet addresses, or signs messages with the keys of those addresses, so anyone can look up the balances on the blockchain.
The liability side is harder. A common method is a Merkle tree: every customer balance is hashed into a tree whose single root summarizes all of them. Each user can check that their own balance is included without seeing anyone else's. Some platforms add zero-knowledge proofs to show that no balance in the tree is negative, and some hire an accounting firm to review the process.
A simple example
Say an exchange's customers are owed 10,000 BTC in total. The exchange publishes addresses holding 10,500 BTC and a Merkle root covering all customer balances, and you find your own 0.5 BTC in the tree. That suggests a reserve ratio of 105% for bitcoin, but only for that snapshot.
Limits and common misunderstandings
A proof of reserves is a snapshot, not a guarantee. Coins can be borrowed for the day of the check and returned afterwards. Reserves only mean something relative to liabilities, so a report that lists assets without customer balances proves very little.
It also usually ignores other debts. A platform may hold enough of each coin for customers but owe large loans to lenders, which a reserve report does not show. It cannot tell you whether the company is solvent overall, whether its keys are secure, or how customers would be treated in an insolvency. Treat it as one data point next to regulation, full financial audits and your own limits on counterparty risk.
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Frequently asked questions
Does proof of reserves mean my funds are safe?
No. It shows that, at one moment, the platform appeared to hold enough of certain assets to match recorded customer balances. It does not cover other debts, future behaviour or security failures.
What is a Merkle tree proof of reserves?
It combines all customer balances into one cryptographic fingerprint, the Merkle root. You can verify that your balance is part of that root without seeing other people's data.
Is proof of reserves the same as an audit?
No. A financial audit examines all assets, liabilities and controls of a company. Most proof-of-reserves reports are narrower checks of specific crypto balances at one point in time.
Related terms
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