Credit Card Processor

What kind of functionality are you looking for? What would you be automating?

If you’re managing memberships you can integrate with Memberful or Patreon… either of those routes are fairly simple to implement with Discourse (and I believe they both also have Wordpress plugins).

If you want to build something completely custom the easiest route might be to setup Wordpress as the SSO provider for your site and your Discourse community, and integrate payments with a service like Stripe (which is who we like to use to process payments) on your Wordpress site…