ActiveMerchant is a gateway-agnostic payments library originally built by Shopify that provides a unified API to dozens of payment processors. It is valuable when you must support multiple gateways or migrate between them without rewriting your application code.
Integration in Rails is simple: add the gem, configure a gateway with credentials, and create purchase, authorise, capture, and refund flows through a consistent interface. It supports Ruby 3+ and works well with Rails 6, 7 and 8, although you should verify the specific adapter you plan to use.
Strengths are breadth of gateway support and a stable, well-known API; weaknesses include variability across gateways and the need to audit the adapter you choose for active maintenance.
Actively maintained alternatives include using the first-party SDKs for Stripe or Braintree when you can standardise on a single provider.
Integration in Rails is simple: add the gem, configure a gateway with credentials, and create purchase, authorise, capture, and refund flows through a consistent interface. It supports Ruby 3+ and works well with Rails 6, 7 and 8, although you should verify the specific adapter you plan to use.
Strengths are breadth of gateway support and a stable, well-known API; weaknesses include variability across gateways and the need to audit the adapter you choose for active maintenance.
Actively maintained alternatives include using the first-party SDKs for Stripe or Braintree when you can standardise on a single provider.