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1
Connect your wallets
Bitcoinnot connectedFistbumpnot connected -
2
Set the terms
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3
Send this to your counterparty
Copy this line to your counterparty — Signal, email, whatever you use. It is just public data: hashlock, your pubkeys, amounts, and the two refund heights.
Show parsed offer
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4
Paste their accept back here
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5
Fund your BTC HTLC
Your wallet will build a standard segwit transaction that locks the BTC into an HTLC that only resolves to them with your preimage or you after the refund height. No one else can touch it.
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6
Wait for them to fund FBC, then claim
Once the counterparty funds the FBC side, your wallet will claim it by broadcasting a transaction that reveals your preimage. The reveal is what lets the counterparty unlock the BTC you posted — that's the atomic part.
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7
If something went wrong — refund your BTC
Only use this if the counterparty never funded their FBC HTLC and the BTC refund height has passed. You can check the current BTC tip on 3xpl.com. Don't touch this if you already claimed FBC in step 6 — your funds are already on their way to the counterparty and trying to refund will just waste a tx fee.
How atomic swaps work
Shared secret
One party generates a 32-byte secret and hashes it. Only the hash is shared. The hash is the puzzle piece; the secret is the key that solves it.
Matching locks
Both chains lock funds into scripts that say: "to spend, either provide the matching secret, or wait until the refund height." Identical logic, two chains.
The reveal
Claiming one side requires putting the secret in the transaction witness — which makes the secret public. The other side uses that same secret to claim.
Or a refund
If anything goes wrong, the refund paths take over after the timelocks. No one can be cheated out of their coins — worst case, you wait and get your money back.