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

# Turnkey + Supertransaction API

> Build secure backend services with Turnkey key management and Biconomy using the REST API

Turnkey works well for backend EIP-7702 flows. This is the minimal Supertransaction API flow: request a quote, sign the 7702 authorization if required, **sign the payload from the API response**, then execute.

<Info>
  Signing the payload is the critical step. The API returns `payloadToSign`, and you must sign it with Turnkey before calling `/v1/execute`.
</Info>

## Minimal EIP-7702 flow

```typescript theme={null}
import { Turnkey } from "@turnkey/sdk-server";
import { createAccount } from "@turnkey/viem";
import { createWalletClient, http } from "viem";
import { base } from "viem/chains";

const turnkey = new Turnkey({
  apiBaseUrl: process.env.BASE_URL, // https://api.turnkey.com
  apiPrivateKey: process.env.API_PRIVATE_KEY,
  apiPublicKey: process.env.API_PUBLIC_KEY,
  defaultOrganizationId: process.env.ORGANIZATION_ID,
});

const account = await createAccount({
  client: turnkey.apiClient(),
  organizationId: process.env.ORGANIZATION_ID,
  signWith: process.env.SIGN_WITH,
});

const walletClient = createWalletClient({
  account,
  chain: base,
  transport: http(),
});

const ownerAddress = account.address;

let quoteResponse = await fetch("https://api.biconomy.io/v1/quote", {
  method: "POST",
  headers: {
    "X-API-Key": "YOUR_API_KEY",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    mode: "eoa-7702",
    ownerAddress,
    composeFlows: [...],
  }),
});

if (quoteResponse.status === 412) {
  const { authorizations } = await quoteResponse.json();
  const signedAuths = await Promise.all(
    authorizations.map(async (authItem) => {
      const authorization = await walletClient.signAuthorization({
        account,
        ...authItem,
      });

      return {
        ...authorization,
        yParity: authorization.yParity,
        v: authorization.v?.toString(),
      };
    })
  );

  quoteResponse = await fetch("https://api.biconomy.io/v1/quote", {
    method: "POST",
    headers: {
      "X-API-Key": "YOUR_API_KEY",
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      mode: "eoa-7702",
      ownerAddress,
      composeFlows: [...],
      authorizations: signedAuths,
    }),
  });
}

const quote = await quoteResponse.json();
const payload = quote.payloadToSign[0];
const signablePayload = payload.signablePayload ?? payload;

const signature = await walletClient.signMessage({
  account,
  message: signablePayload.message,
});

await fetch("https://api.biconomy.io/v1/execute", {
  method: "POST",
  headers: {
    "X-API-Key": "YOUR_API_KEY",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    ...quote,
    payloadToSign: [{ ...payload, signature }],
  }),
});
```