• What is a PayPal API signature?
  • PayPal classic interface

Connecting PayPal to Billed lets your clients pay invoices using their PayPal balance, linked bank account, or credit card — all from a Pay Now button on the invoice itself. To set up the integration you need three credentials from PayPal: your API Username, API Password, and API Signature. This guide shows you how to find them in both the classic and modern PayPal interfaces.

Key Takeaways

  • Your PayPal API signature consists of three credentials: API Username, API Password, and API Signature found in your account settings
  • In the classic PayPal interface, navigate to Profile > My Selling Tools > API Access to generate or view your credentials
  • Once connected, clients can pay invoices using PayPal balance, linked bank accounts, or credit cards directly from your invoice

What is a PayPal API signature?

PayPal's NVP/SOAP API uses a set of three credentials to authenticate your account with third-party applications like Billed. These credentials are separate from your regular PayPal login and are used exclusively for programmatic access. You need a PayPal Business or Premier account to generate them — personal accounts do not support API signatures.

PayPal classic interface

If you see the older PayPal layout, follow these steps:

  1. Log in to your PayPal business account at paypal.com (or sandbox.paypal.com for testing).
  2. Click the Profile icon in the top-right corner and select Profile and Settings. If you do not see the profile icon, look for Profile under the My Account tab.
  3. In the left menu, click My selling tools.
  4. Under the Selling online section, find API access and click the Update link.
  5. On the API Access page, click Manage API credentials.
  6. If you have already generated a signature, the page will show a View API Signature link. You can use the existing credentials or remove them and generate new ones.
  7. Select Request API signature, then click Agree and Submit.
  8. Copy the API Username, API Password, and API Signature.

PayPal modern interface

If you see the newer PayPal business dashboard:

  1. Log in to your PayPal account.
  2. Hover over the Tools menu in the top navigation and click All Tools.
  3. Scroll down until you find the API credentials card and click it. If a left sidebar appears after clicking All Tools, click Integrate PayPal and then find the API Credentials card.
  4. Shortcut: Click this link to go directly to the Tools page.
  5. On the API credentials page, scroll to the NVP/SOAP API integration section (usually the last option) and click it.
  6. If this is the first time you are creating credentials, complete the API Credential Request form.
  7. Once generated, click View API Signature under the NVP/SOAP section. Click Show next to each field to reveal the API Username, API Password, and API Signature.
  8. Copy all three values.

Connect PayPal to Billed

  1. In Billed, go to Settings > Payment Gateways > PayPal.
  2. Paste the API Username, API Password, and API Signature into the corresponding fields.
  3. Click Save.

Every invoice you send will now include a Pay Now button that lets clients pay through PayPal. Payments land in your PayPal business account, where you can transfer them to your bank.

Test mode vs. live mode

PayPal's Sandbox environment lets you test the integration without processing real money. Use your Sandbox API credentials (generated at sandbox.paypal.com) to verify everything works, then switch to your live credentials before sending invoices to clients.

Keeping your credentials secure

API credentials give programmatic access to your PayPal account. Follow these precautions:

  • Never share them publicly. Treat them like a password.
  • Store them securely. Do not save credentials in plain text files, emails, or shared documents.
  • Regenerate if compromised. If you suspect your credentials have been exposed, remove the existing API signature in PayPal and create a new one immediately. Update the new credentials in Billed right away.

Troubleshooting

  • "Invalid credentials" error — Double-check that you copied all three values (Username, Password, and Signature) and that there are no extra spaces before or after each value.
  • Pay Now button not showing — Make sure you saved the credentials in Billed and that the PayPal gateway is toggled on.
  • Payments not arriving — Confirm you are using live credentials, not Sandbox credentials. Sandbox transactions do not move real money.
  • Cannot find API credentials page — You need a PayPal Business or Premier account. Personal accounts do not support API signatures. Upgrade your account type in PayPal settings if needed.

Why offer PayPal on your invoices?

PayPal is one of the most widely used payment platforms in the world. Many clients already have a PayPal account and prefer it for business transactions because it provides buyer protection and works across currencies. Offering PayPal alongside Stripe gives clients flexibility and helps you get paid faster.

Related Articles

Ready to put this into practice? Billed lets you send invoices and accept online payments for free.

Frequently Asked Questions

Where do I find my PayPal API signature in my account settings?

Log in to your PayPal business account, go to Settings, then Account Settings, then API Access under Website Payments. Select "Manage API Credentials" to view or generate your API signature, username, and password. These three credentials together are needed for NVP/SOAP API integrations.

Do I need a PayPal business account to get an API signature?

Yes, API credentials are only available for PayPal Business accounts, not personal accounts. If you currently have a personal account, you can upgrade to a business account for free through PayPal's settings, which will then give you access to API credentials and other merchant features.

Is the PayPal API signature the same as the API key?

No, PayPal uses different credential types depending on the API version. The API signature is used with the older NVP/SOAP APIs and consists of a username, password, and signature string. For the newer REST APIs, PayPal uses a Client ID and Secret instead, which you generate from the PayPal Developer Dashboard.

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