Here's the API doc of Stripe: https://stripe.com/docs/api They seem to be using a three-columns template. I am wondering whether they use some API blueprint renderer (markdown-to-html type of script) to generate it, similarly to Aglio: https://github.com/danielgtaylor/aglio
If they don't use any renderer, what other types of API blueprint renderers exist out there?
Stripe uses an in house doc generation tool, but Slate (https://github.com/tripit/slate) is a tool modeled off of Stripe's documentation. It looks quite similar and may be what you're looking for. I haven't used it myself so unfortunately I can't tell you much more.
If you want to stick to API Blueprint markdown flavor then check out apiary (http://apiary.io) as an alternative to aglio. It's not the three column layout but it is nice looking.