I'm looking for generic and open source payment libraries that support many different payment processor APIs. In other words, I'd like to develop an application using a single payment processing API, but be able to easily switch between payment gateways, such as Authorize.Net, Payflow Pro, Braintree, PayPal, Google, Amazon, etc.
This question gives some Java solutions, but the suggestions all look horrible. Isn't there anything more like ActiveMerchant for Java? I really need a good Java solution, to the point of building my own if necessary. But I don't want to reinvent the wheel if it exists.
Are there any solutions for Python, Node.JS, or PHP?
Ideally, I'd like to find something similar to Ruby's ActiveMerchant, which looks exceptionally complete. Are there any other Ruby solutions?
You can embed JRuby in your JVM and start using any ruby libraries you want!Same is valid for any other JVM languages!
There's a python port of ActiveMerchant called OpenMerch, which looks quite similar to the ActiveMerchant code.
There is django-bursar for use with django.
omnipay is the best solution for PHP
You can checkout J2pay its clean and its supported gateway list is continuously increasing.
What I have seen done is just wrapping Active Merchant into a light weight web service which exposes a rest API that any of your languages can talk to. This was for a larger company that could properly lock down their networks though, so DYODD.