> ## Documentation Index
> Fetch the complete documentation index at: https://docs.buckspay.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Node / Core - @buckspay/core

> Use createBuckspayClient directly - no React. Suitable for server scripts, CLI tools, and backend workers.

`@buckspay/core` is the platform-agnostic heart of the SDK. You can use it directly - without
any React layer - in Node.js scripts, backend workers, or any environment where you control
the signer manually.

The surface is the same three-phase flow described in [Prepare -> Sign -> Send](/concepts/prepare-sign-send):
`createBuckspayClient` assembles the client; `createRpcSimContext` gives `prepare()` a Soroban
simulator; then `connect()` -> `pay()` (or the split `prepare` / `sign` / `send`) executes the
payment.

<Steps>
  ### Install

  ```bash theme={null}
  pnpm add @buckspay/core @buckspay/accounts @buckspay/signers @buckspay/relayer
  ```

  ### Create the client

  ```ts theme={null}
  import { createBuckspayClient, createRpcSimContext } from "@buckspay/core";
  import { classicAccount } from "@buckspay/accounts/classic";
  import { walletsKit } from "@buckspay/signers/wallets-kit";
  import { buckspayFacilitator } from "@buckspay/relayer/buckspay-facilitator";

  const client = createBuckspayClient(
    {
      network: "testnet",
      account: classicAccount(),
      signer: walletsKit({ network: "testnet" }),
      relayer: buckspayFacilitator({ url: "/api/gasless", network: "testnet" }),
      gas: { mode: "sponsored" }
    },
    createRpcSimContext("https://soroban-testnet.stellar.org")
  );
  ```

  ### Connect and pay

  ```ts theme={null}
  await client.connect();
  const call = client.transfer({ token: USDC_SAC, to: MERCHANT, amount: "1.50" });
  const receipt = await client.pay([call]);
  console.log(receipt.transferTx);
  ```
</Steps>

## When to use the core directly

| Scenario                               | Recommended approach                                                                             |
| -------------------------------------- | ------------------------------------------------------------------------------------------------ |
| React / React Native app               | [`@buckspay/react`](/platforms/web-react) or [`@buckspay/react-native`](/platforms/react-native) |
| Next.js App Router BFF route           | [`@buckspay/nextjs`](/platforms/nextjs-bff)                                                      |
| Node.js script, backend worker, or CLI | `@buckspay/core` directly                                                                        |
| Server-side relay (any framework)      | `createBuckspayClient` + `buckspayFacilitator({ apiKey })` - server-only                         |

<Note>
  When using `@buckspay/core` in a server-side relay, pass `apiKey` to `buckspayFacilitator`
  as an environment variable. The API key must never appear in a browser bundle.
</Note>

## Full quickstart example

```ts theme={null}
// Quickstart - classic gasless USDC transfer (browser; NO apiKey).
import { createBuckspayClient, createRpcSimContext } from "@buckspay/core";
import { classicAccount } from "@buckspay/accounts/classic";
import { walletsKit } from "@buckspay/signers/wallets-kit";
import { buckspayFacilitator } from "@buckspay/relayer/buckspay-facilitator";

const USDC_SAC: string = "CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA";
const MERCHANT: string = "GA6HCMBLTZS5VYYBCATRBR5VBZJEH5C2OON6XQGB3RNYDDAQ7JZ65YQH";

export async function quickstart(): Promise<void> {
  const buckspay = createBuckspayClient(
    {
      network: "testnet",
      account: classicAccount(),
      signer: walletsKit({ network: "testnet" }),
      // url points at YOUR backend, which forwards to the facilitator with the key server-side.
      relayer: buckspayFacilitator({ url: "/api/gasless", network: "testnet" }),
      gas: { mode: "sponsored" }
    },
    // prepare() simulates against the Soroban RPC.
    createRpcSimContext("https://soroban-testnet.stellar.org")
  );

  await buckspay.connect(); // wallet + ensureReady
  const call = buckspay.transfer({ token: USDC_SAC, to: MERCHANT, amount: "1.50" });
  const receipt = await buckspay.pay([call]); // prepare -> sign -> send
  console.log(receipt.transferTx); // settled on testnet
}
```

## Next

<CardGroup cols={2}>
  <Card title="Quickstart" href="/get-started/quickstart">
    The full quickstart walkthrough with a classic G-address account.
  </Card>

  <Card title="Prepare -> Sign -> Send" href="/concepts/prepare-sign-send">
    The three-phase flow and where the BFF slot fits.
  </Card>
</CardGroup>