What is an incremental snapshot?

An incremental snapshot is a session replay event that describes a change to the page since the previous event, such as a DOM mutation, a mouse move, a scroll or an input, rather than the whole document.

Why it matters

Recording the full document on every change would be far too heavy. Instead, DOM recording takes one full snapshot when recording starts and then emits a stream of incremental snapshots. Playback applies them in order, exactly like replaying a database log.

This is why a replay can be seeked, paused and resumed precisely, and why an idle page costs almost nothing to record. It also means a recording is only as complete as its event stream: drop a mutation and everything after it may render wrongly.

How AnyReplay handles it

AnyReplay uses the event types of rrweb unchanged and groups them into chunks of 200 events or 5 seconds, sent in sequence so the server can detect gaps and duplicates. The React Native SDK follows the same principle for the element tree: the first frame of a screen is a few kilobytes and every later frame carries only what changed. Translation is applied to the event stream itself, so a translated string stays translated through every later incremental snapshot.