SDK version dimension
SDK version is the dimension that records which version of the measurement SDK — the gtag.js tagging build on web, or the Google Analytics for Firebase SDK in apps — produced an event. It is collection-layer metadata, not a visitor attribute. Its main value is diagnostic: when a metric shifts after a release, splitting by SDK version separates an instrumentation change from a genuine behaviour change.
What this means
The SDK version dimension records the version of the measurement library that sent an event — gtag.js on the web, the Firebase Analytics SDK in mobile apps. It is metadata about how data was collected, not about who triggered it.
It is most useful when you are auditing data quality across instrumentation changes.
Isolating collection changes
When a metric jumps after a deploy, segmenting by SDK version tells you whether the change is concentrated in a newly-rolled-out build — implying a tagging or SDK cause — or spread evenly, implying a real behavioural shift. During staged rollouts, multiple SDK versions coexist, and comparing them is a fast triage step.
This turns 'did the number really change?' into a testable question.
- Records the gtag.js / Firebase SDK build
- Collection metadata, not a user attribute
- Splits instrumentation change from real change
How it appears in analytics and logs
An SDK version value identifies the collection build behind an event. A metric anomaly confined to one SDK version points at a tagging or SDK issue, not user behaviour.
Diagnostic use case
Use SDK version to confirm a metric movement followed an SDK or tagging upgrade, isolating collection changes from real user-behaviour shifts.
What WebmasterID can help detect
WebmasterID can record which collection build emitted an event as first-party diagnostic context, helping separate measurement bugs from real change.
Common mistakes
- Treating SDK version as a user or device attribute.
- Ignoring it when triaging post-deploy metric anomalies.
- Assuming one SDK version during a staged rollout.
Privacy and accuracy notes
SDK version is collection metadata, not personal data. WebmasterID treats instrumentation versions as first-party diagnostic context, never as an identifier.
Related pages
- App version dimension
The app version dimension reports which build of your mobile app a session ran. GA4/Firebase reads it from the app's version string automatically. This page explains how it is populated, why multiple versions coexist in the wild, and how version skew affects event and funnel analysis.
- Platform dimension (web, Android, iOS)
Platform is the dimension that labels the broad surface an event came from — web, Android, or iOS — based on which data stream collected it. In a property that mixes a website and apps, it is the first cut for comparing surfaces. It is coarser than device category (which splits desktop/mobile/tablet within web) and complements the data stream ID, which is the precise per-stream key.
- Data stream ID dimension
Data stream ID is the dimension that records the numeric identifier of the GA4 data stream an event came from. A GA4 property can have web, Android, and iOS streams, and each event is stamped with its origin stream_id. It is the stable machine key for splitting reports by platform source, distinct from the editable stream name. It is configuration metadata, not anything about the visitor.
- Website observability
Separate collection bugs from real change.
Sources and verification notes
- GA4 Data API — Schema (dimensions)Lists the SDK version dimension exposed via the API.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.