Invoice Ninja + PayPal REST

Current configuration

Item	Value
Invoice Ninja	https://invoice.id86.net
Invoice Ninja version	5.13.26
PayPal gateway	PayPal REST (PayPal_Rest)
Environment	Sandbox / test mode
Currency	USD
PayPal app	opshell
Gateway status	Configured and active for company 1

Credentials are stored in ~/.ssh/paypal/.env; they are not written into this documentation or the Invoice Ninja repository.

Configuration applied

• PayPal REST gateway created for the Invoice Ninja company.
• Sandbox Client ID and Secret configured.
• testMode enabled.
• PayPal funding method enabled.
• Billing and shipping addresses are not required for digital/service invoices.
• Company gateway setting updated so the gateway is active in the client portal.

Verification

Invoice Ninja's own PayPalRestPaymentDriver successfully obtained a Sandbox OAuth access token from:

https://api-m.sandbox.paypal.com/v1/oauth2/token

The invoice page exposes PayPal as the available payment method. No customer payment has been captured yet.

Example invoice

Item	Value
Invoice number	0001
Amount	$10.00 USD
Client	PayPal Sandbox Test - Donnyaw
Recipient	donnyaw@gmail.com
Email status	Sent through the Docker mailserver
Public invoice URL	https://invoice.id86.net/client/invoice/qy8IAeK9VmN73JIDjl9UPw4qF30hFHfi
PayPal method	Available on the invoice page

The email was resent after correcting the company portal domain from the internal server URL to https://invoice.id86.net.

End-to-end test

1. Create a USD test invoice in Invoice Ninja.
2. Open the invoice through the client portal.
3. Select Pay Now → PayPal.
4. Sign in with the Sandbox personal account from Testing Tools → Sandbox Accounts.
5. Approve the payment.
6. Confirm the invoice changes to paid in Invoice Ninja.

Webhooks

Invoice Ninja handles the normal PayPal payment return and payment recording. The separate Webhook Endpoint is optional for event logging, reconciliation, notifications, and future membership provisioning.

Troubleshooting

If Invoice Ninja reports invalid credentials:

• Confirm PayPal Sandbox credentials are used while testMode is enabled.
• Confirm the credential pair belongs to the opshell Sandbox app.
• Clear application cache with php artisan optimize:clear inside the app container.
• Check Invoice Ninja logs under /var/www/app/storage/logs/.

Do not switch to live credentials until the Sandbox invoice flow succeeds.