Under the REST API apps section, either select an existing app or create a new one to get your sandbox and live API credentials.
Step 2: Add the PayPal SDK to Your Theme
Go to Shopify Admin > Online Store > Themes.
Find your theme and click “Actions” > “Edit code”.
Open theme.liquid found under the “Layout” folder.
Add the PayPal SDK script on the line before , replacing “YOUR_SANDBOX_CLIENT_ID” with your actual sandbox client ID.
Step 3: Insert the PayPal Button Container
In main-cart.liquid, locate the code for the checkout button.
Directly below this button, insert the container for the PayPal button:
Step 4: Add JavaScript to Render the PayPal Button
Still in main-cart.liquid, below the SDK script, add the JavaScript to render the PayPal button and handle payment. Additionally, ensure it captures the total cart amount:
Step 5: Test the Integration
Save your changes in main-cart.liquid.
Visit your cart page on your Shopify site to see the PayPal button.
Conduct a test transaction using your sandbox account to ensure everything works as expected.
Step 6: Prepare for Going Live
Replace the sandbox client ID in the SDK script with your live client ID.
Test the integration with a real transaction to confirm everything works in live mode.
Monitor transactions and user feedback for any issues that might arise.
Step 7: Final Checks
Ensure mobile responsiveness.
Verify that the PayPal payment option does not interfere with other payment methods.
Check the user experience for smoothness and clarity.
Please note that I have just implemented these steps after 5 hours of figuring them out. I have applied them only to the cart page for now, not the product page. I will integrate them into the product page soon and will send you updates on how I manage it if it succeeds.