How does a server SDK differ from a client SDK?

The server library knows what the system actually completed but nothing about the user's device or page; the client library is the opposite. Most products end up using both: behaviour from the browser, outcomes from the server.

Server SDK

Intermediate

Updated Jul 11, 2026 Shahin editorial 2 min read

PronunciationEN/ˈsɜːrvər ˌɛs diː ˈkeɪ/

A server SDK is an analytics library installed in backend code that sends events from your own servers instead of from the user's browser or app.

It runs in a trusted server environment, so nothing is automatic: the user identity, the timestamp and any device or campaign context have to be passed in explicitly. Because it is not in the page, ad blockers, browser storage limits and closed tabs do not affect it, which makes it the right place for money-critical events such as a confirmed payment. The usual trap is expecting the enrichment a browser SDK provides for free; a server event with no forwarded context lands in reports as unknown device and unknown source. Long-running processes also need an explicit flush before shutdown, or the last queued batch never leaves.

FAQ

Sources:Google — Measurement Protocol (GA4)