REST API credentials include a client ID and secret. Here's how you generate the credentials:

1. Log in to the PayPal Developer Portal using the same credentials you use for PayPal.
2. On the My Apps & Credentials page, click Live or Sandbox depending on whether you need an app for testing (Sandbox) or going live (Live).
3. Click Create App under REST API apps. Any previously created REST API apps will appear in the table above the Create App button.
4. Enter the name of your REST API app in the App Name field, and select a Sandbox business account to associate with your app.
   Note: Remember that you can't use a Live credit card in Sandbox, and you can't use a test credit card in your Live account.
5. Click Create App.
   Your credentials, the client ID and secret, are displayed on the app details page that displays after you click Create App.
6. Request permissions for REST API features that apply to your integration, such as:
   • Invoicing API
   • PayPal Here
   • Subscriptions
   • PayPal payments
   • Connect with PayPal
   • Customer Disputes API
   • Payouts
7. When you are ready to take your code live, make sure you create a Live app to get live credentials.

Use the Live and Sandbox toggle at the top of My Apps & Credentials to swtich between app types and view your credentials for each.

Notes:

• You should be able to complete transactions in the Live environment right away.
• Both environments use the same URL. Only the REST API credentials (Client ID and Secret) tell you which environment you're in.
• Don't share your Live REST API credentials with anyone.

Refer to Get Started on the PayPal Developer Portal for more information about getting credentials, an access token, and creating sandbox test accounts.