Before beginning your integration, you need to set up your development environment. You can refer to this flow diagram, and watch a video demonstrating how to integrate PayPal standard Checkout.

Start your integration by grabbing the sample code from PayPal’s GitHub repo, or visiting the PayPal GitHub Codespace. Read the Codespaces guide for more information. You can also use Postman to explore and test PayPal APIs. Read the Postman Guide for more information.

1. Integrate front end CLIENT

Set up your front end to integrate standard checkout payments.

Front-end process

1. Your app shows the PayPal checkout buttons.
2. Your app calls server endpoints to create the order and capture payment.

Front-end code

This example uses a index.html file to show how to set up the front end to integrate standard payments.

The /src/index.html and /src/app.js files handle the client-side logic and define how the PayPal front-end components connect with the back end. Use these files to set up the PayPal checkout using the JavaScript SDK and handle the payer's interactions with the PayPal checkout button.

You'll need to:

• Save the index.html file in a folder named /src.
• Save the app.js file in a folder named /src.

Step 1. Add the script tag

Include the <script> tag on any page that shows the PayPal buttons. This script will fetch all the necessary JavaScript to access the buttons on the window object.

Step 2. Configure your script parameters

The snippet in Step 1. Add the script tag shows that you need to pass a client-id and specify which components you want to use. The SDK offers Buttons, Marks, Card Fields, and other components. This sample focuses on the buttons component.

In addition to passing the client-id and specifying which components you want to use, you can also pass the currency you want to use for pricing. For this exercise, we'll use USD.

Buyer Country and Currency are only for use in sandbox testing. These are not to be used in production.

Step 3. Render the PayPal buttons

After setting up the SDK for your website, you need to render the buttons.

The paypal namespace has a Buttons function that initiates the callbacks needed to set up a payment.

The createOrder callback launches when the customer clicks the payment button. The callback starts the order and returns an order ID. After the customer checks out using the PayPal pop-up, this order ID helps you to confirm when the payment is completed.

Completing the payment launches an onApprove callback. Use the onApprove response to update business logic, show a celebration page, or handle error responses.

If your website handles shipping physical items, this documentation includes details about our shipping callbacks.

Step 4. Configure the layout of the Buttons component OPTIONAL

Depending on where you want these buttons to show up on your website, you can lay out the buttons in a horizontal or vertical stack. You can also customize the buttons with different colors and shapes.

To override the default style settings for your page, use a style object inside the Buttons component. Read more about how to customize your payment buttons in the style section of the JavaScript SDK reference page.

Step 5. Support multiple shipping options OPTIONAL

Integrate shipping options to offer your buyers the flexibility to choose their preferred delivery method. Buyers can update their shipping address and select from your shipping options.

• The onShippingAddressChange callback is triggered when the buyer selects a new shipping address. Use the data in this callback to tell the buyer if you support the new shipping address, update shipping costs, and update the line items in the cart.

• The onShippingOptionsChange callback is triggered when the buyer selects a new shipping option. Use the data in this callback to tell the buyer if you support the new shipping method, update shipping costs, and update the line items in the cart.

Visit the JavaScript SDK reference page for more details about the onShippingAddressChange and onShippingOptionsChange callbacks.

2. Integrate back end SERVER

This section explains how to set up your backend to integrate standard checkout payments.

The PayPal Server SDK provides integration access to the PayPal REST APIs. The API endpoints are divided into distinct controllers:

• Orders Controller: Orders API v2
• Payments Controller: Payments API v2

Backend process

• Your app creates an order on the backend by calling to the ordersCreate method in the Orders Controller. See Create Orders V2 API endpoint.
• Your app calls the ordersCapture method in the Orders Controller on the backend to move the money when the payer confirms the order. See Capture Payment for Order V2 API endpoint .

Backend Code

The sample integration uses the PayPal Server SDK to connect to the PayPal REST APIs. Use the server folder to setup the backend to integrate with standard payments flow.

• The server side code runs on port 8080
• Declare the PAYPAL_CLIENT_ID and PAYPAL_CLIENT_SECRET as environment variables. The server side code is configured to fetch these values from the environment to authorize the calls to the PayPal REST APIs.
• By default the server SDK clients are configured to connect to the PayPal's sandbox API.

Step 1. Generate access token

Initialize the Server SDK client using OAuth 2.0 Client Credentials (PAYPAL_CLIENT_ID and PAYPAL_CLIENT_SECRET). The SDK will automatically retrieve the OAuth token when any endpoint that require OAuth 2.0 Client Credentials is invoked.

Step 2. Create Order

You need a createOrder function to start a payment between a payer and a merchant

Set up the createOrder function to make a request to the ordersCreate method in the Orders Controller and pass data from the cart object to calculate the purchase units for the order.

See the Create order endpoint of the PayPal Orders v2 API for sample responses and other details.

Step 3: Capture Payment

You need a captureOrder function to to move money from the payer to the merchant

Set up the captureOrder function to make a request to the ordersCapture method in the Orders Controller and pass the orderID generated from the Create Order step.

See the Capture Payment for Order V2 API endpoint for sample responses and other details.

3. Custom Integration OPTIONAL

Handle buyer checkout errors

Use onError callbacks and alternate checkout pages to handle buyer checkout errors.

If an error prevents buyer checkout, alert the user that an error has occurred with the buttons using the onError callback. This error handler is a catch-all. Errors at this point are not expected to be handled beyond showing a generic error message or page.

If a null pointer error prevents the script from loading, provide a different checkout experience.

Handle funding failures

If your payer's funding source fails, the Orders API returns an INSTRUMENT_DECLINED error. A funding source might fail because the billing address associated with the payment method is incorrect, the transaction exceeds the card limit, or the card issuer denies the transaction. To handle this error, restart the payment so the payer can select a different payment option.

Show cancellation page

Show a page to your payers to confirm that the payment was cancelled.

Refund a captured payment

Refund a captured payment from a seller back to a buyer.

4. Test integration

Before going live, test your integration in the sandbox environment. Learn more about card testing, simulating successful payments using test card numbers and generating card error scenarios using rejection triggers.

Test the following use cases before going live:

PayPal Payment

Test a purchase as a payer:

1. Select the PayPal button on your checkout page.
2. Log in using one of your personal sandbox accounts. This ensures the payments will be sent to the correct account. Make sure that you use the sandbox business account that corresponds to the REST app you are using.
3. Note the purchase amount in the PayPal checkout window.
4. Approve the purchase with the Pay Now button. The PayPal window closes and redirects you to your page, indicating that the transaction was completed.

Confirm the money reached the business account:

1. Log in to the PayPal sandbox using the sandbox business account that received the payment. Remember that the SDK source now uses a sandbox client ID from one of your REST apps, and not the default test ID.
2. In Recent Activity, confirm that the sandbox business account received the money, subtracting any fees.
3. Log out of the account.

Card payment

1. Go to the checkout page for your integration.
2. Generate a test card using the credit card generator.
3. Enter the card details in the hosted field, including the name on the card, billing address, and 2-character country code. Then, submit the order.
4. Confirm that the order was processed.
5. Log in to your merchant sandbox account and navigate to the activity page to ensure the payment amount shows up in the account.

5. Go live

Follow this checklist to take your application live.

1. Log into the PayPal Developer Dashboard with your PayPal business account.
2. Obtain your live credentials.
3. Include the new credentials in your integration and Update your PayPal endpoint.

See Move your app to production for more details.