Hyperswitch

Stripe

stripe/stripe-node

Popular

Developer-first payments platform for checkout, billing and Connect; stripe-node is its official SDK.

PayPal

developer.paypal.com

Popular

Global wallet and payments platform with checkout SDKs, Venmo and Braintree card processing.

Adyen

adyen.com

Enterprise payments platform unifying online, mobile and in-person processing.

Paddle

paddle.com

Merchant-of-record billing platform that handles global sales tax, invoicing and subscriptions for SaaS.

Lemon Squeezy

lemonsqueezy.com

Merchant-of-record payments for digital products and SaaS, owned by Stripe since 2024.

Polar

polarsource/polar

Rising

Open-source merchant-of-record platform for digital products, subscriptions and usage-based billing.

Lago

getlago/lago

Open-source metering and usage-based billing engine; an alternative to Stripe Billing.

Kill Bill

killbill/killbill

Mature open-source Java subscription billing and payments platform.