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

# Flex Checkout Quick Start

> Flex Checkout is our low-code integration to accept HSA/FSA payments.

At this point you should have a Flex account, access to the partner dashboard, and have gone through the onboarding process of adding your payout information with Stripe.

Below we walk through a full example of how to integrate Flex Checkout into your checkout flow.

## Flex Checkout guide

<Steps titleSize="h3">
  <Step title="Create an API Key in the partner dashboard">
    <Warning>
      If you're just getting started, be sure to create an API Key in test mode to
      safely distinguish between testing and production.
    </Warning>

    In the partner dashboard, navigate to the **Developers** section. Here you'll find
    an **API Keys** tab where you can create a key to interact with Flex.

    Select the `New API Key` button and give your key a name. With this key, you can now
    make authenticated requests to the Flex API.
  </Step>

  <Step title="Define a product to sell">
    Always keep sensitive information—like price and availability—on your server to
    prevent customer-side manipulation. Define product data when creating the Checkout
    Session using predefined price IDs or on the fly with `price_data`.

    For this example, we've created a product eligible via a Letter of Medical Necessity.
    To learn more, see the [Product docs](/developer-guides/products-and-prices/how-products-and-prices-work) or
    the Product API.

    ```bash theme={null}
    curl --request POST \
      --url https://api.withflex.com/v1/products \
      --header 'authorization: Bearer fsk_test_YzNiYjdhNWItN2FkOS00ZTMyLWE5MmQtZTdhNzMzYzE2NTIy' \
      --header 'content-type: application/json' \
      --data '{"product": {"name": "Test Product","description": "Test Product Description"}}'
    ```

    ```json theme={null}
    {
      "product": {
        "product_id": "fprod_01HW5MXAPBE79RHMMJJGB4ACAB",
        "name": "Test Product",
        "description": "Test Product Description",
        "created_at": "2024-04-23T14:14:16.029253Z",
        "active": true,
        "upc_code": null,
        "gtin": null
      }
    }
    ```
  </Step>

  <Step title="Define the price for our product">
    Using the returned `product_id`, create a one-time price for \$50.99:

    ```bash theme={null}
    curl --request POST \
      --url https://api.withflex.com/v1/prices \
      --header 'authorization: Bearer fsk_test_YzNiYjdhNWItN2FkOS00ZTMyLWE5MmQtZTdhNzMzYzE2NTIy' \
      --header 'content-type: application/json' \
      --data '{"price": {"product": "fprod_01HW5MXAPBE79RHMMJJGB4ACAB","description": "Our awesome new price","unit_amount": 5099}}'
    ```

    ```json theme={null}
    {
      "price": {
        "price_id": "fprice_01HW5NTAB88NK7HPD0H688EPG9",
        "description": "Our awesome new price",
        "unit_amount": 5099,
        "recurring": null,
        "active": true,
        "product": "fprod_01HW5MXAPBE79RHMMJJGB4ACAB",
        "created_at": "2024-04-23T14:30:05.943282Z",
        "type": "one_time",
        "metadata": null
      }
    }
    ```
  </Step>

  <Step title="Choose the mode">
    Checkout supports two modes: `payment` (one-time purchases) or `subscription`.
    Learn more about subscription and setup modes in the docs.
  </Step>

  <Step title="Supply success and cancel URLs">
    Specify publicly accessible URLs so Flex can redirect after checkout:

    * `success_url`: `https://withflex.com/thank-you?success=true`
    * `cancel_url`:  `https://withflex.com/thank-you?canceled=true`
  </Step>

  <Step title="Build your checkout">
    On your site's order preview page, add a button that calls your server to generate
    a checkout session.
  </Step>

  <Step title="Generate a checkout session">
    On your server, create a session with your line items and redirect URLs:

    ```bash theme={null}
    curl --request POST \
      --url https://api.withflex.com/v1/checkout/sessions \
      --header 'authorization: Bearer fsk_test_YzNiYjdhNWItN2FkOS00ZTMyLWE5MmQtZTdhNzMzYzE2NTIy' \
      --header 'content-type: application/json' \
      --data '{
        "checkout_session": {
          "line_items": [{"price": "fprice_01HW5NTAB88NK7HPD0H688EPG9","quantity": 1}],
          "success_url": "https://withflex.com/thank-you?success=true",
          "cancel_url": "https://withflex.com/thank-you?canceled=true",
          "mode": "payment"
        }
      }'
    ```
  </Step>

  <Step title="Redirect users to checkout">
    The response includes a `redirect_url`—send the user there to complete payment:

    ```json theme={null}
    {
      "checkout_session": {
        "redirect_url": "https://checkout.withflex.com/pay/c/fcs_01HW5Q2A08N6A0YGZ6T1KARN8S",
        …
      }
    }
    ```
  </Step>

  <Step title="Try it out">
    Navigate to the returned `redirect_url` and test with these cards:

    * Success: `4242 4242 4242 4242`
    * Decline: `4000 0000 0000 9995`
  </Step>

  <Step title="Congratulations!">
    You now have a basic checkout integration working 🎉
  </Step>
</Steps>

## Fulfillment

Set up a [webhook](/developer-guides/integration/checkout/fulfillment) to fulfill orders after a payment succeeds.

## Explore checkout session scenarios

Depending on your setup/business you may want to rely on additional parameters that are available as part of the Checkout Session API.
Some of the common scenarios, can be found [here](/developer-guides/integration/checkout/guides).