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

# Crypto Lending Quickstart

> Walk through the four Flex endpoints — fetch plans, invest, check status, withdraw — in under 5 minutes.

The four endpoints below cover the full Flex lifecycle — fetch plans, invest, check status, withdraw — operating against Main balance and authenticated with a key that has the Trade permission.

## Prerequisites

* A WhiteBIT account with completed KYC ([register](https://whitebit.com/auth/register))
* An API key with **Trade** permission ([create key](https://whitebit.com/settings/api))
* Funds in [Main balance](/concepts/balances) (the lending API operates on Main balance, not Trade balance)
* HMAC-SHA512 signing configured ([authentication guide](/api-reference/authentication))
* `curl` and `jq` installed (for command-line examples)

<Note>
  The quickstart uses **Flex plan** endpoints, which are available to all authenticated users.
  Fixed plan endpoints require B2B partner permissions -- see the [overview](/products/lending/overview) for details.
</Note>

<Steps>
  <Step title="Fetch available Flex plans">
    Retrieve the list of available Flex plans to find a plan ID for investment.

    <Tabs>
      <Tab title="cURL">
        ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
        curl -X POST https://whitebit.com/api/v4/main-account/smart-flex/plans \
          -H "Content-Type: application/json" \
          -H "X-TXC-APIKEY: YOUR_API_KEY" \
          -H "X-TXC-PAYLOAD: YOUR_PAYLOAD" \
          -H "X-TXC-SIGNATURE: YOUR_SIGNATURE" \
          -d '{"request": "/api/v4/main-account/smart-flex/plans", "nonce": 1709340000000}'
        ```
      </Tab>

      <Tab title="Python">
        ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
        import requests, json, hmac, hashlib, base64, time

        API_KEY = "YOUR_API_KEY"
        API_SECRET = "YOUR_SECRET"
        BASE_URL = "https://whitebit.com"

        def make_request(endpoint, body):
            nonce = int(time.time() * 1000)
            body["request"] = endpoint
            body["nonce"] = nonce
            data_json = json.dumps(body)
            payload = base64.b64encode(data_json.encode())
            signature = hmac.new(
                API_SECRET.encode(), payload, hashlib.sha512
            ).hexdigest()
            headers = {
                "Content-Type": "application/json",
                "X-TXC-APIKEY": API_KEY,
                "X-TXC-PAYLOAD": payload.decode(),
                "X-TXC-SIGNATURE": signature,
            }
            return requests.post(f"{BASE_URL}{endpoint}", headers=headers, data=data_json)

        # Fetch available Flex plans
        response = make_request("/api/v4/main-account/smart-flex/plans", {})
        plans = response.json()
        print(json.dumps(plans, indent=2))
        ```
      </Tab>
    </Tabs>

    For Go and PHP examples, see [SDKs](/sdks).

    **Expected response:**

    ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
    [
      {
        "id": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
        "ticker": "USDT",
        "minInvestment": "10.0",
        "maxInvestment": "100000.0",
        "maxRate": "0.15"
      },
      "..."
    ]
    ```

    Save the `id` value from a plan to use in the next step.
  </Step>

  <Step title="Create a Flex investment">
    Invest into the selected Flex plan using the plan ID from Step 1.

    <Tabs>
      <Tab title="cURL">
        ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
        curl -X POST https://whitebit.com/api/v4/main-account/smart-flex/investments/invest \
          -H "Content-Type: application/json" \
          -H "X-TXC-APIKEY: YOUR_API_KEY" \
          -H "X-TXC-PAYLOAD: YOUR_PAYLOAD" \
          -H "X-TXC-SIGNATURE: YOUR_SIGNATURE" \
          -d '{
            "plan": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
            "amount": "100.00",
            "withReinvest": true,
            "request": "/api/v4/main-account/smart-flex/investments/invest",
            "nonce": 1709340000001
          }'
        ```
      </Tab>

      <Tab title="Python">
        ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
        # Create a Flex investment (use plan ID from Step 1)
        response = make_request("/api/v4/main-account/smart-flex/investments/invest", {
            "plan": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
            "amount": "100.00",
            "withReinvest": True,
        })
        print(response.json())
        ```
      </Tab>
    </Tabs>

    **Required fields:** `plan` (UUID from Step 1), `amount` (string). **Optional:** `withReinvest` (boolean, enables auto-reinvestment).

    **Expected response:**

    ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
    {
      "data": {
        "transaction_id": "tx_9f3e0d4c-2b5c-4d3e-8f6g-7a8b9c0d1e2f"
      }
    }
    ```
  </Step>

  <Step title="Check investment status">
    Verify the investment was created and check the current investment status.

    <Tabs>
      <Tab title="cURL">
        ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
        curl -X POST https://whitebit.com/api/v4/main-account/smart-flex/investments \
          -H "Content-Type: application/json" \
          -H "X-TXC-APIKEY: YOUR_API_KEY" \
          -H "X-TXC-PAYLOAD: YOUR_PAYLOAD" \
          -H "X-TXC-SIGNATURE: YOUR_SIGNATURE" \
          -d '{"request": "/api/v4/main-account/smart-flex/investments", "nonce": 1709340000002}'
        ```
      </Tab>

      <Tab title="Python">
        ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
        # Check active investments
        response = make_request("/api/v4/main-account/smart-flex/investments", {})
        investments = response.json()
        print(json.dumps(investments, indent=2))
        ```
      </Tab>
    </Tabs>

    **Expected response:**

    ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
    {
      "data": [
        {
          "id": "inv_7e2d9c3b-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
          "planId": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
          "currency": "USDT",
          "invested": "100.00",
          "withAutoReinvest": true,
          "status": 1,
          "..."
        }
      ],
      "..."
    }
    ```
  </Step>

  <Step title="Withdraw from investment">
    Withdraw funds from the Flex investment back to Main balance.

    <Tabs>
      <Tab title="cURL">
        ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
        curl -X POST https://whitebit.com/api/v4/main-account/smart-flex/investments/withdraw \
          -H "Content-Type: application/json" \
          -H "X-TXC-APIKEY: YOUR_API_KEY" \
          -H "X-TXC-PAYLOAD: YOUR_PAYLOAD" \
          -H "X-TXC-SIGNATURE: YOUR_SIGNATURE" \
          -d '{
            "plan": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
            "amount": "50.00",
            "request": "/api/v4/main-account/smart-flex/investments/withdraw",
            "nonce": 1709340000003
          }'
        ```
      </Tab>

      <Tab title="Python">
        ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
        # Withdraw from Flex investment (partial withdrawal)
        response = make_request("/api/v4/main-account/smart-flex/investments/withdraw", {
            "plan": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
            "amount": "50.00",
        })
        print(response.json())
        ```
      </Tab>
    </Tabs>

    **Required fields:** `plan` (UUID), `amount` (string). Partial withdrawals are supported. To withdraw everything, use the full invested amount.

    **Expected response:**

    ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
    {
      "data": {
        "transaction_id": "tx_9f3e0d4c-2b5c-4d3e-8f6g-7a8b9c0d1e2f"
      }
    }
    ```
  </Step>
</Steps>

After completing Step 4, the withdrawn amount returns to the [Main balance](/concepts/balances). Verify by checking the [Main balance endpoint](/api-reference/account-wallet/overview).

## What's Next

<CardGroup cols={2}>
  <Card title="Crypto Lending Overview" icon="book-open" href="/products/lending/overview">
    Fixed vs Flex plan mechanics, B2B partner permissions for Fixed endpoints, \~90 supported assets, and auto-invest behavior.
  </Card>

  <Card title="API Reference" icon="square-terminal" href="/api-reference/account-wallet/overview">
    Full endpoint documentation for all 13 lending endpoints.
  </Card>
</CardGroup>

For Go and PHP examples, see [SDKs](/sdks).