How do I check whether someone really sent me bitcoin?

1. Look up your own address

Copy the address you gave the sender from your own wallet, not from their message, and paste it into UTXOHub’s search. The address page lists every payment to it, with its amount and whether it is waiting or confirmed. You don’t need anything from the sender for this, so it is the quickest check. If nothing has been paid to the address at about the time they say they sent it, no payment has reached you there, whatever they show you. Your wallet’s own history should agree once it has updated.

2. Or ask for the transaction ID

Ask the sender for the payment’s full transaction ID as text you can copy, not as a picture. It is 64 characters of digits and the letters a to f. Paste it into UTXOHub’s search yourself, rather than opening a link the sender sends you, since a link they choose can open a page that only looks like an explorer. On the payment’s page, check each of these:

• One of its outputs pays your address. Compare the whole address, every character, not just its start and end.
• That output’s amount is what you agreed. The total of all outputs includes the sender’s change and anyone else paid, so don’t read that.
• Its status says confirmed, with how many confirmations, or says it is still waiting.

Why a screenshot, receipt or email proves nothing

Anyone can make a picture of a payment. The wallet company imToken warns that “screenshots of wallet transaction pages, blockchain explorer pages, and exchange withdrawal records can all be fabricated”. In a case it describes, a seller of tokens sent a screenshot marked Successful, with the right address and amount, and the buyer paid; nothing had been sent. An email can be faked the same way. Consumer Affairs Victoria warns that scammers posing as buyers send emails that seem to come from a payment company, saying you were paid, or overpaid. The payment is real only if you can find it yourself, at your own address.

A payment that is still waiting can disappear

Finding the payment is the first step. If it is waiting to confirm, it has zero confirmations, and Bitcoin.org warns that “unconfirmed transactions aren’t secure”. Until a miner puts it in a block, the sender’s wallet can replace it with a new version that spends the same bitcoin with a higher fee, and that version can pay someone else, including the sender. Since Bitcoin Core 28.0, nodes accept such a replacement by default. So a screenshot of a pending payment, or even a real pending payment, isn’t yet a payment you can count on. Once it is in a block it has one confirmation, and each block after that makes it harder to reverse. How many to wait for is your decision; no number suits every amount.

Signs the payment isn’t real

Be careful if the sender can’t give you a transaction ID, keeps sending screenshots instead, or hurries you to hand something over. A real sender can always copy the ID from their wallet’s history. Be more careful still if anyone asks you to pay first: an “activation fee”, a deposit, or a charge to “release” or “unlock” the bitcoin. imToken tells its users never to pay one, and a real Bitcoin payment needs nothing from the person receiving it. If someone says they paid you too much and asks for the difference back, check what has actually confirmed to your address first. A Bitcoin payment can’t be reversed, only refunded by whoever received it, so money you send back is gone.

If you can’t find the payment

Check that you searched the full address or ID, and that the sender used the Bitcoin network. A payment over Lightning, a faster network built on top of Bitcoin, isn’t a separate Bitcoin transaction, so only the Lightning wallets at each end can show it. Some apps also move bitcoin between two of their own customers without any Bitcoin transaction: Coinbase does this when you send to another Coinbase user’s email, phone number or username. Then only the app can show the payment. If the sender says they sent it from a wallet to your Bitcoin address, there should be a transaction to find; ask them for its ID.