How does a swap service match your deposit to your order without an account

05 September 2026

It uses a unique, one-time deposit address generated specifically for your order. You send your crypto to that address, and the service knows which order it belongs to because no other customer will ever receive that same address.

This is the core trick. A swap service that does not hold accounts or user profiles still needs a way to link your incoming deposit to the exchange rate and destination you selected a few minutes earlier. The solution is simple: create a fresh address on the source blockchain for every single order, then present that address to you before you send anything. The address itself becomes the identifier.

The process works like this. You arrive on the site, choose your source asset and amount, choose your destination asset, and provide a return address (in case something goes wrong). The service's software generates a new receiving address on the source blockchain, stores it in a database alongside your order details, and shows it to you on screen. You copy that address and send your coins. When the service's wallet monitoring system sees a transaction arriving at that address, it checks the database to find the matching order. The destination transaction is then sent to the address you provided.

Why does the service need a return address at all? If the deposit address is the identifier, why not just use it for everything? Because the deposit address lives on the source blockchain, and the destination asset lives on a different blockchain. The service cannot send you coins on chain B using an address on chain A. The return address is a separate, chain-specific destination for the asset you want to receive. It also serves as a fallback - if the swap fails partway, the service can return your original coins to that same address.

A few practical details matter. The generated deposit address is typically a new, unused key that the service controls. It is not recycled; after the swap completes or expires, that address is retired. This prevents confusion if someone else later sends coins to the same address. It also means you do not need to label or memo anything - the address itself is the label. On blockchains that support optional memos or destination tags, the service may combine a fixed address with a unique memo, but the principle is the same: the combination is unique to your order.

You might wonder how the service funds all those fresh addresses. It maintains a large pool of funded addresses on each supported chain. When an order is created, one address from the pool is assigned to you. The service's wallet software rotates through them, replenishing balances as needed. The pool is not infinite, but it is large enough that the same address is not reused for an active order.

There is a limit to how long the service waits. Most swap services set an expiry time - often 15 to 60 minutes - after which the generated address is invalidated. If you send coins after expiry, the service may still process the deposit, but the exchange rate will be recalculated at the current market price. Some services return the coins to your return address instead. The exact behaviour varies.

This system is the foundation of the "no account" swap. It eliminates the need for you to create a login, store credentials, or trust the service with a persistent balance. The trade-off is that you must complete the deposit within the time window, and you must ensure you send the correct asset and amount to the generated address. Errors - sending the wrong token, using the wrong network, or underpaying - are not automatically fixable, because there is no account to correct them in. Those scenarios are covered in the sibling pages of this set, particularly the one about sending a token on the wrong network.

If you want the full picture of how these swaps fit together, read the hub page "Swapping crypto across chains." It explains the broader mechanics, including what happens when you use a bridge versus a swap service, and why the return address requirement makes sense.

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