CRYPTO

Atomic Swaps Tutorial

Atomic Swaps Tutorial

Atomic Swaps

An atomic swap lets two people exchange cryptocurrencies across different blockchains without trusting each other or handing coins to a third party. The swap either completes fully or refunds both sides — there is no in-between where one party walks away with both assets.

Benefits

  • No KYC required
  • No centralized exchange
  • Direct peer-to-peer
  • Enhanced privacy

How the Trustless Mechanism Works

Atomic swaps use Hash Time-Locked Contracts (HTLCs) — smart contracts on each blockchain that lock funds behind a matching cryptographic condition and a timeout:

  • Both sides lock their funds (e.g., your BTC and the counterparty's XMR) in separate HTLCs tied to the same secret hash
  • When both sides reveal the secret, each HTLC releases the swapped funds to the other party — the swap completes atomically
  • If the timeout expires before both sides cooperate, each HTLC automatically returns the locked funds to their original owner — no one loses coins to the other side

Neither party ever needs to trust the other or deposit coins with an intermediary. The blockchain enforces the rules.

Step-by-Step: BTC to XMR Swap

Use a swap tool such as UnstoppableSwap (desktop app) or a COMIT-based interface. The flow is the same in principle:

  1. Choose your swap tool and open a new BTC→XMR swap
  2. Lock in the exchange rate for a short window — confirm the quoted amount of XMR you will receive
  3. Send your BTC to the swap's HTLC address shown by the tool
  4. Wait for the counterparty to lock their XMR on the Monero side
  5. The swap completes automatically once both locks are in place and the secret is exchanged — XMR arrives in your wallet
  6. If the counterparty never locks or the rate window expires, your BTC is refunded automatically when the HTLC timeout triggers

Risks and Limits

  • Rate-lock windows are short — once you accept a quote, send your BTC promptly; a delayed transaction can miss the window and force a restart
  • Liquidity and minimums vary — not every tool supports every pair at every amount; check the tool's current limits before starting
  • No customer support to appeal to — unlike a regular exchange, a wrong address or incorrect amount is irreversible; double-check both before confirming