# Buy on the marketplace

Reserve, prepare, sign, and broadcast, with the checks that stop you paying for something that already moved.

Page ID: guides/buy-on-marketplace
Applicability: universe-implementation
Authority: universe-implementation
Networks: mainnet
Verified: 2026-08-31
Locale: en
URL: https://bitcoinuniverseio.github.io/atomicals-and-arc-20/guides/buy-on-marketplace/

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## Before you start

- Supported networks: mainnet.
- Status: Universe implementation.
- Your funding inputs must be confirmed and uncoloured. Spending a coloured output to fund a
  purchase loses those units.

## The lifecycle

1. **Read the listing.** Record the Atomical ID, the price, and the exact payment script.
2. **Reserve.** A reservation holds the listing while you prepare. Read the reservation back.
3. **Prepare the purchase.** The service builds the settlement transaction and returns what you
   must sign.
4. **Sign.** With the exact scope the prepare step specifies.
5. **Validate signed.** The service checks your signed material against the blueprint before
   anything is broadcast.
6. **Broadcast.** Only after validation passes.
7. **Verify settlement.** See [verify settlement](/guides/verify-settlement/).

## What is validated before broadcast

- The seller still controls the asset, at a stable checkpoint.
- Your funding inputs are confirmed, uncoloured in both the script hash view and location history,
  and of a supported type.
- The Atomicals blueprint assigns the selected asset cleanly to the buyer output, with no
  operation, no mixed Atomical ID, and no burn.
- Heights and hashes on both sides are unchanged across the bracket.

Anything else fails closed.

## Check before signing

| Check | Why |
| --- | --- |
| The Atomical ID matches the listing | A ticker or name is not identity |
| The price is exactly what you agreed | Including any disclosed marketplace fee |
| Your funding inputs are cardinal | Or you spend an asset to buy one |
| Every output is visible with script and value | You cannot verify what you cannot see |
| The signature scope | It must not let outputs change after you sign |

## If it fails

| Failure | Meaning |
| --- | --- |
| Reservation expired | Reserve again. The listing may be gone |
| Stale ownership | The seller moved the asset. Nothing was spent |
| Mixed collateral | The seller's output carries more than the asset |
| Checkpoint drift | The chain moved mid-check. Retry |
| Validation failed | Do not broadcast. Start again |

A failure before broadcast costs nothing.

## Fees

The price, the settlement transaction fee, and any disclosed marketplace fee. The flow must show
the breakdown before your final confirmation.

## Source

[Marketplace v1](/reference/api/marketplace-v1/) and
[transfers and swaps](/protocol/arc20/transfers-and-swaps/).