Best Open Source Alternatives to PayPal

Invoice Ninja is an open-source, self-hosted invoicing and billing platform that replaces single-rail tools with multi-gateway client management.

vs PayPal: a free, open-source option you fully control, licensed AGPL-3.0.

BTCPay Server is a self-hosted crypto payment processor that lets teams accept Bitcoin with zero transaction fees and full control over private keys.

vs PayPal: a free, open-source option you fully control, licensed MIT.

Kill Bill is an open-source billing platform replacing Stripe Billing with self-hosted subscription lifecycles and multi-gateway payment routing.

vs PayPal: a free, open-source option you fully control, licensed Apache-2.0.