I'm a developer looking to integrate a payment gateway and invoicing system for multiple sites with different products and categories. Is there a good combined payment gateway and invoicing solution for this scenario?

My main requirements are

Must run on a Windows server, preferrably .NET
A decent API, particularly for the payment processing
Source code available (not strictly necessary but a big bonus)
Ability to access API remotely (I can build the services, as long as the API doesn't have dependencies on the ASP.NET runtime)
Ability to process payments with New Zealand payment gateway DPS (Payment Express). Even if this isn't built in, as long as the code has affordance for me to implement this feature myself.


I have spent the past couple of days working with DotNetInvoice but have discovered that the API and source code is of very poor quality and can't do what I need.

Obviously a lower price is always better but I will consider almost anything.

Any help would be very much appreciated.

Tricky question. There aren't a lot of good billing systems around for Windows, probably because open source software is not widely available for Windows.

I think you'll need to look into coding your own system, or finding something open source that you can then code to your needs.

Blesta is very customizable(Coding wise)..doesn't run on Windows as far as I know but its easy to play with.

I've heard nothing but good about Google Merchant Services.

Yeah i got to agree it has to be google merchant. I have heard loads of good things about them. They are good prices too