# On-chain Buy

The Registry API expands the domain registration options by offering a direct-to-blockchain mothod for registering domains. The API is [publically available](https://docs.unstoppabledomains.com/apis/registry/#tag/domains) and retrieves both domain pricing and pre-approval for purchase which are sent to the `Buy` function on the [smart contract](https://polygonscan.com/address/0x7be83293BeeDc9Eba1bd76c66A65F10F3efaeC26#writeProxyContract).

## Check Domain Availability

The Registry API provides a [domain availability endpoint](https://docs.unstoppabledomains.com/apis/registry/#operation/GetDomain) for checking registration status of a domain name.

To use this endpoint, you will need to include the domain name of interest and one of our [supported domain endings](https://docs.unstoppabledomains.com/apis/resolution/#operation/StatusController.listSupportedTlds) as part of the API query. For example, checking the availability of `qwerty.wallet` would look like this:


```typescript
const data = fetch(`https://api.unstoppabledomains.com/registry/v1/domains/qwerty.wallet`, {
  method: "GET",
});
```

Which would yield the below JSON response.


```json
{
    "name": "qwerty.wallet",
    "availability": {
        "status": "AVAILABLE",
        "price": {
            "listPrice": {
                "usdCents": 75000
            },
            "subTotal": {
                "usdCents": 75000
            }
        }
    }
}
```

## Request Purchase Transaction Details

Once you have confirmed the domain is available, you can request the transaction details for purchasing the domain and minting it to a specific wallet address.

Continuing with the `qwerty.wallet` example, make a `POST` request to the [purchase parameters endpoint](https://docs.unstoppabledomains.com/apis/registry/#operation/PostDomainPurchaseParameters) with a payload indicating the claiming wallet address, any crypto records that should be set on mint, as well as the currency the domain will be purchased in.

An example payload would be:


```json
{
    "owner": { 
      "address": "0x1234567890123456789012345678901234567890" 
    },
    "records": {
      "crypto.ETH.address": "0x6EC0DEeD30605Bcd19342f3c30201DB263291589",
      "crypto.BTC.address": "bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh"
    },
    "currency": "MATIC"
}
```

Currently `MATIC` is the only supported currency.

You will get JSON response that confirms the domain availability and pricing, as well as the encoded transaction details such as:


```json
{
...
"params": {
            "to": "0x7be83293BeeDc9Eba1bd76c66A65F10F3efaeC26",
            "data": "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",
            "value": "0x342006d851f399d89d"
        }
}
```

### Send Transaction

With the above transaction details, you are now able to use your Web3 library of choice to send the transaction. Using `ethers` as an example:


```typescript
const provider = new ethers.providers.Web3Provider(library.provider);
const params = {
  to: txParams.to,
  data: txParams.data,
  value: txParams.value,
};

const signer = provider.getSigner();
await signer.sendTransaction(params);
```

The specified owner will recieve the domain as a result of a `successful` transaction.

That's it! You are now able to purchase Unstoppable domains on chain.