Stripe

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.

Hyperswitch

juspay/hyperswitch

Open-source, Rust-based payments switch for routing transactions across multiple processors.

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.