Proof of Reserves: What It Proves and What It Doesn't
Proof of reserves shows an exchange holds certain assets at one moment. Learn how it works, how to verify your balance, and the gaps it leaves unchecked.
Proof of reserves (PoR) shows that a crypto exchange or custodian controlled certain assets at a specific moment and, in better versions, that those assets covered the customer balances it reported at that same moment. What it does not prove is that the company is solvent overall, that the assets weren't borrowed, or that the situation stayed the same after the snapshot.
Proof of reserves became widely adopted after the collapse of the FTX exchange in November 2022, when customers discovered their deposits weren't there. Many exchanges now publish reserve reports, and they are a useful transparency tool. But they are easy to over-interpret, so it's worth knowing exactly what is and isn't covered.
How Proof of Reserves Works
A complete proof of reserves usually has two halves: assets and liabilities.
Proving assets
The exchange shows it controls certain blockchain addresses. Common methods include:
- Signing a message with the private keys of those addresses.
- Moving a specific small amount from those addresses at an agreed time.
- Publishing the address list so anyone can check balances on a block explorer.
Proving liabilities
The exchange takes a snapshot of every customer's balance and builds a Merkle tree: a structure that combines all balances into one cryptographic fingerprint (the "Merkle root"). Each customer can check that their balance is included without seeing anyone else's details.
Some exchanges add zero-knowledge proofs to show that no account has a negative balance and that the total adds up correctly without revealing individual balances.
Comparing the two
If the assets shown are equal to or greater than the customer liabilities in the snapshot, the exchange claims a reserve ratio of 100% or more.
What Proof of Reserves Proves
| It can show | Conditions |
|---|---|
| The exchange controlled certain addresses | If ownership was cryptographically demonstrated |
| Those addresses held certain balances | At the snapshot time |
| Your balance was included in the liabilities | If you verify your own entry in the Merkle tree |
| Customer crypto balances were covered | Only for the assets included in the report |
What Proof of Reserves Doesn't Prove
- Overall solvency. Customer balances are only some of a company's liabilities. Loans, debts and legal claims usually aren't included.
- Ownership versus borrowing. An exchange could temporarily borrow assets to show them at snapshot time.
- Continuity. The report shows one moment. Funds can be moved minutes later.
- Encumbrance. Assets might be pledged as collateral elsewhere.
- Completeness of liabilities. Leaving some accounts out of the Merkle tree makes the ratio look better. Individual users can only check their own inclusion.
- Operational safety. It says nothing about hacking risk, key management or governance.
- Legal protection. It doesn't tell you what happens to your funds if the company fails. See our guide on what happens to your crypto if an exchange goes bankrupt.
Attestations vs Audits
Many reserve reports involve an accounting firm, but the type of engagement matters. A narrow attestation or agreed-upon procedures report checks specific items at a point in time. A full financial statement audit reviews the company's overall finances, controls and liabilities. When reading a report, check who prepared it, what scope they were given and what they explicitly did not check.
A Simple Example
Imagine an exchange reports customer Bitcoin balances of 10,000 BTC and shows addresses holding 10,500 BTC, a reserve ratio of 105%. That sounds reassuring. But suppose the company also owes 3,000 BTC to a lender, a debt not included in the report. Its real position is 10,500 BTC of assets against 13,000 BTC of obligations. The reserves check passes, yet the company could not repay everyone. This is exactly the gap that liabilities-free reports leave open.
How to Read a Proof of Reserves Report
Use this checklist:
- 1Which assets are covered? All customer assets, or only major coins like Bitcoin?
- 2Are liabilities included, with a Merkle tree you can verify yourself?
- 3What is the reserve ratio for each asset? A high total ratio can hide shortfalls in specific coins.
- 4How often is it published? Monthly or more frequent reports are more informative than one-off reports.
- 5Who verified it, and what was the scope?
- 6Can you trace the addresses on a block explorer? Our guide on how to use a block explorer helps.
- 7Are the assets the exchange's own tokens? Reserves held largely in a token the exchange issued are weaker evidence.
How to Verify Your Own Balance
If an exchange offers Merkle tree verification:
- 1Log in and find the proof of reserves or "verify my assets" page.
- 2Note your account identifier or hash for the snapshot.
- 3Confirm that your balance at the snapshot time matches your records.
- 4Optionally use the exchange's open-source tool to recompute the path to the Merkle root.
If your balance is missing or wrong, contact support and keep records of your query.
Using Proof of Reserves in Exchange Due Diligence
Proof of reserves works best combined with other checks, such as licensing, security history and how customer assets are held. Our due diligence checklist for centralized exchanges covers the full list, and you can compare platforms on the exchanges page at Certified Crypto Market.
The safest approach doesn't depend on any exchange's report: keep only what you need for trading on exchanges and hold long-term funds in a wallet you control.
Bottom line
Proof of reserves can show that an exchange held specific assets covering customer balances at a single point in time. It does not prove solvency, rule out borrowed funds or guarantee your money is safe tomorrow. Read the scope, verify your own balance where you can, and use it as one signal among many.
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What is proof of reserves?
Proof of reserves is a process in which a crypto custodian, usually an exchange, shows that it controls enough assets to cover customer balances. It typically combines evidence of wallet ownership on-chain with a cryptographic summary of customer balances that individual users can check their own account against.
Does proof of reserves mean an exchange is solvent?
Not necessarily. Solvency means total assets exceed total liabilities. Proof of reserves usually covers only customer crypto balances at one point in time and may not show loans, debts or other obligations the company has. An exchange could pass a reserves check and still be insolvent.
How can I check my balance is included in proof of reserves?
Exchanges that use a Merkle tree approach usually provide a verification page or tool. You enter or receive a unique identifier and confirm that your balance at the snapshot time was included in the published data. Some exchanges also provide open-source tools so you can verify independently.
Is proof of reserves the same as an audit?
No. A proof of reserves report is usually much narrower than a full financial statement audit. It often comes from an agreed-upon procedures engagement or an attestation that covers specific assets at a specific time, rather than a full review of the company's finances, controls and liabilities.