We've split the backend into a service layer written in Go, a data fetching and processing layer also written in Go, and a web layer written in Python/Coffeescript. We use Kafka to connect a lot of the pieces together, and data is stored in PostgreSQL and Cassandra.

This is awesome. Congrats on the launch Flo :)

Oh hi Erik, cool to see you here and thanks! Haven't seen you in way too long.

@ericflo will probably pop by and answer a little bit more, but the major pieces are a golang powered API stack, a Django app that consumes that API stack and does all the template rendering and such, and a lot of background workers based around Kafka/Storm to pull the data from the third party services. @aprilzero can certainly talk more about the frontend stack.

Originally it was Python and now a combination of Python & Go.

He wrote a couple of articles about how he build the service for himself and it used Python with Django so it's safe to assume he stuck with that stack https://aprilzero.com/journal/making-of-aprilzero/ (he's whole site seems to be down now, perhaps the HN effect)