[wenbin]

It's built from scratch, which was easier than customizing from some open source projects back then (early 2019).

But the doc is codified in openapi format: https://www.listennotes.com/api/docs/#openapi

So you can feed the openapi spec into other doc viewers, e.g., Postman, or redoc https://listen-api.listennotes.com/api/v2/openapi.html