PayPal payments

Accept PayPal payments on invoices alongside (or instead of) Stripe. When PayPal is enabled, the public invoice pay page shows a Pay $amount button (Pay with PayPal when more than one provider is on); the customer approves on PayPal's hosted page, the payment is captured on return, and it records in SlowBooks with the same journal entries as any online payment (DR Undeposited Funds / CR Accounts Receivable, or the clearing account and fee when Post to a clearing account is on).

See Stripe payments for the Stripe equivalent — both can be enabled at once. The notes there on who can change these settings, where the pay link works and USD-only invoices apply to PayPal too.

Prerequisites

• A PayPal Business account (paypal.com/business)
• Slowbooks Pro running and accessible

Step 1: Create a REST API app

1. Log in to the PayPal Developer Dashboard
2. Go to Apps & Credentials
3. Start in Sandbox mode (toggle at the top) for initial testing
4. Click Create App, name it (e.g. "Slowbooks"), and create it
5. Copy the Client ID and Secret for the app

Step 2: Configure Slowbooks

1. Open Settings → Online Payments → PayPal (an administrator's setting)
2. Set PayPal Payments to Enabled
3. Set Environment to Sandbox (switch to Live after testing)
4. Paste the Client ID and Client Secret
5. Save

Step 3 (server installs): Add a webhook

Skip this on desktop installs — webhooks can't reach 127.0.0.1; payments record automatically when the customer returns from PayPal, or via the Check Payment Status button on the invoice. (On a desktop or LAN install the pay link itself only opens on your own network, see the Stripe guide.)

1. In the developer dashboard, open your app → Webhooks → Add Webhook
2. URL: https://your-server/api/payments/paypal/webhook (PayPal delivers to HTTPS on port 443 only)
3. Subscribe to the event Payment capture completed (PAYMENT.CAPTURE.COMPLETED)
4. Save, then copy the Webhook ID into Slowbooks settings

Step 4: Test in sandbox

1. Use the default sandbox personal (buyer) account PayPal made for you under Testing Tools → Sandbox Accounts, or create one
2. In Slowbooks, open an unpaid invoice → Copy Payment Link → open it in a private window
3. Click Pay with PayPal, log in with the sandbox buyer account, approve
4. On return you should see "Payment received — thank you!"
5. Verify in Slowbooks: the invoice is Paid, a payment row exists (method paypal), and the journal entry posted

Going live

Switch the app credentials to the Live tab in the developer dashboard, paste the live Client ID/Secret into Slowbooks, set Environment to Live, and (server installs) recreate the webhook against the live app.

Notes

• Amounts are charged in USD for the invoice's balance due at checkout time.
• Approval and capture are separate steps at PayPal; Slowbooks captures on the customer's return (idempotently), and the webhook is a second, redundant recording path on server installs.
• Refunds are issued from the PayPal dashboard. In SlowBooks, void the online payment for a full refund (the posting reverses, through the clearing account when that is on) or enter a credit memo for a partial one.