Snowplow: how does a sequence of actions become a dataset?

What does Snowplow do?

Snowplow supplies tools for collecting structured records of activity. An app includes a software development kit (SDK): a reusable package of code. It records events, such as opening a screen or starting a video, and sends them to a collector, a server that accepts those records. The publisher chooses its implementation; a Snowplow system can use a publisher's own domain.

An event can carry context and identifiers. An identifier is a value used to recognise the same installation, session or account again. Snowplow documents several identifiers, with different lifetimes and sources. Its mobile documentation also describes device language, timezone and screen information. Which fields an app supplies and which privacy settings it uses must be checked separately. Snowplow identifiers, mobile properties.

Why does an identifier matter?

Hypothetical example: three records say “radar opened”, “place selected” and “subscription screen opened”. With one installation ID, an analyst can put these actions in sequence. Counting three unrelated clicks gives a different picture from observing one returning installation. This example explains the mechanism; it is not a captured Buienradar session.

What did our inspected apps actually contain?

In Buienradar 7.4.8, the app creates RTL and DPG trackers for nl-rtl-prod1.collector.snplow.net and c.dpgmedia.net. Traced events include screen, element, funnel, purchase, radar-location and login activity. A funnel measures successive steps through a flow. Install-referrer and lifecycle tracking also cover installation origin and app activity states. The Kantar/NMO plugin passes the Snowplow user ID as cs_fpid; see Kantar/NMO. The audit also found a hard-coded consent context. That is a code finding, not a legal conclusion about consent. Pinned Buienradar audit.

NU.nl, de Volkskrant, Trouw, AD and Parool have separately audited publisher tracking paths, including tracking-module.api.dpgmedia.cloud. Shared technology does not make their exact coverage identical. Destination evidence.

What changes after patching?

Buienradar's Disable tracking stops tracker creation and the app dispatcher, covering its attached NMO plugin too. The news-app controls stop their inventoried dispatch, queues and known web collectors. Necessary content, account and notification services remain. These source and output checks do not establish zero traffic or erase records already held by a server.

Evidence reviewed 28 October 2026. Continue with how tracking works, identifiers and our methodology.