Glossary · Tracking technology
What is session replay?
Session replay is a feature that records the changes to a web page and a visitor's interactions with it — mouse movement, clicks, scrolling, typing events — and reconstructs them later as a video-like playback of that visit.
Also called: Session recording, Screen recording
Updated
How does session replay work?
It isn't screen video. A script snapshots the page's DOM, then records every change (mutations, scroll positions, pointer movement, inputs) as small events, usually with an open-source library like rrweb. The player rebuilds the page from those events. That's why replays are light enough to collect at scale, and why masking can happen before anything leaves the browser.
What session replay is good for
- Seeing *why* a funnel step loses people.
- Reproducing bugs users report but can't describe.
- Spotting rage clicks on things that look clickable but aren't.
- Watching how first-time visitors read a landing page.
Session replay example
Checkout drop-off on mobile is twice desktop's. Five replays of mobile visitors who dropped show the same thing: the coupon field opens the keyboard, which covers the pay button, and people give up. No metric would have told you that; five minutes of replays did.
Privacy safeguards
- Mask all form inputs by default and never record what people type.
- Mask or block elements that show personal data.
- Keep recordings short-lived and access-controlled.
- Disclose session recording in your privacy notice; in the EU, recording usually needs a careful lawful-basis assessment and often consent.
Session replays in VisitTrack
Replays are opt-in and off by default. When turned on (20% of sessions by default, adjustable from 1% to 100%), the server tells the tracker to load a separate recorder (replay.js, about 24 KB gzipped, built on rrweb) only for sampled, non-bot visits; every form field is masked and what people type is never recorded; data-vt-mask and data-vt-block hide your own elements; nothing is stored in the visitor's browser; recordings are deleted automatically after 30 days and are visible only to your team, never on public dashboards. Replays don't count toward your event usage. See session replays.
Frequently asked questions
Is session replay legal under GDPR?
It can be, with care: mask personal data, minimize what's recorded, keep retention short, disclose it in your privacy notice and assess the lawful basis, which in the EU is often consent. This is general information, not legal advice.
Does session replay slow down a website?
A well-built recorder adds little overhead because it records DOM changes rather than video and uploads in small batches, but it is extra JavaScript. Loading it only on a sample of visits keeps the cost low.
Related terms
- HeatmapA website heatmap is a visualization that overlays a page with colors showing where visitors clicked, how far they scrolled, or where they moved their pointer — warm colors for high activity, cool colors for low.
- Funnel drop-offFunnel drop-off is the share of visitors who complete one step of a funnel but don't reach the next one — the leak between two stages of a conversion path.
- GDPRGDPR, the General Data Protection Regulation (Regulation (EU) 2016/679), is the European Union law that governs how personal data about people in the EU is collected, used and stored, in force since May 25, 2018.
- Event trackingEvent tracking is recording specific actions visitors take on a website or app — clicks, form submissions, sign-ups, downloads, purchases — as named events, often with properties that describe them.
- Consent bannerA consent banner, or cookie banner, is the notice a website shows to ask visitors for permission before storing or reading non-essential cookies and similar identifiers on their device, and to record their choice.
Tools and guides
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