What is a cross-chain swap and how does it settle without a bridge

05 September 2026

A cross-chain swap is a direct exchange of one cryptocurrency for another on a different blockchain, and it settles without a bridge by using an atomic swap protocol that either completes both transfers or cancels them entirely. No intermediary holds your funds. No third-party network validates the exchange. The swap is a single, cryptographically enforced transaction that spans two blockchains.

How atomic swaps work

The core mechanism is a hash time-locked contract (HTLC). The process goes like this:

1. You generate a secret value, hash it, and send the hash to the other party.
2. You create a contract on your chain that locks your coins. The contract says: the other party can claim these coins if they provide the secret that matches the hash, within a set time. If time expires, your coins return to you.
3. The other party, seeing your contract, creates a similar contract on their chain, locking their coins. Their contract uses the same hash and a shorter time window.
4. You claim the other party's coins by revealing the secret. This action automatically exposes the secret on their chain.
5. The other party then uses that revealed secret to claim your coins on your chain.

If either party walks away, the time locks expire and each side's coins return to their original owner. No coins are ever held by a third party. No bridge is needed because the two blockchains never communicate directly - only the participants do, through the shared secret.

Why this matters for getting assets across chains

Bridges are custodial or semi-custodial systems that lock tokens on one chain and mint representations on another. They introduce attack surfaces: the bridge's smart contracts, its validators, or its operators. Atomic swaps eliminate those surfaces. You hold your private keys throughout. The swap either settles completely or not at all.

The trade-off is that atomic swaps require both blockchains to support the same cryptographic primitives - typically hash functions and time locks. Bitcoin, Litecoin, and many Ethereum-compatible chains do. Chains that lack these features cannot participate directly.

Practical limits

Atomic swaps are not a general solution for moving arbitrary tokens. They work best for native coins (like swapping BTC for ETH) or for tokens that are themselves native to their chain. Swapping an ERC-20 token for a BEP-20 token via atomic swap is possible only if both chains support the same contract standard and the same hash-lock mechanism - which most do not.

The swap also requires both parties to be online and cooperative during the time window. If one side goes offline after locking coins, the other must wait for the time lock to expire before reclaiming funds.

Where this fits in the broader picture

The hub page "Swapping crypto across chains" covers the full range of methods for moving value between blockchains. Atomic swaps are one option - useful when you want a trustless, one-to-one exchange without a bridge or a centralised account. They are not the fastest method, nor the most convenient for casual users. But they are the only method that settles entirely on the underlying chains, with no extra layer to trust.

If you need to understand how the other methods compare - centralised exchanges, wrapped tokens, liquidity networks - the hub page is the next thing to read. Each approach trades off speed, cost, security, and complexity. Atomic swaps trade convenience for sovereignty.

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