---
search:
  tags:
    - Usage
    - GET
seo:
  description: >-
    Rank your Kafka topics by the data volume they moved over a date range,…
    Reference for the GET /billing/usage/top-topics endpoint in the Streamkap
    REST API.
sidebar:
  label: Top topics by data volume
  badge: GET
title: Top topics by data volume
type: openapi-operation
---
Rank your Kafka topics by the data volume they moved over a date range, largest first, with everything past the requested limit folded into an `others` rollup so the parts add up to the total. Volumes are returned in both bytes and decimal GB.

Unlike the other usage endpoints, which report six fixed rolling windows, this one takes an explicit range — so it is the one that can answer which topics drove a given month's bill. `end_date` is exclusive.

`direction=in` ranks by what your sources ingested; `direction=out` by what your destinations delivered. Out-direction figures are per topic consumed, so a topic read by several destinations appears once with their combined volume.

`GET /billing/usage/top-topics`