I often use BuiltWith to find out what technology, CMS, Scripts or Analytics a website has used. However it does not track what payment methods a website has used to implement its subscriptions based payments model. Are there any tools or service that I can use to find it out?
Some great suggestions Brandon!
And it sounds like you're already using a lot of great insight tools. I'm not totally sure what you are looking for data wise, but what I've found to work in a lot of situations is simply using the Chrome Inspect tool. Essentially;
1. I right click over the object I'm interested in, and then click Inspect.
2. Dig around through the layers and look for anything insightful such as a domain name etc that tips me off to what's powering it (eg Infusionsoft, Mailchimp, plugin etc).
The other thing that might help is Firefox's inspect tool since it has 3D which helps you "see" into the code and find things more simply.
Hope that's helpful!