What Is Session Replay: How It Works And Why It Matters

Session replay software captures user interactions and reconstructs them as video-like playbacks without recording actual screen video. The technology logs events and page structure to reproduce what happened during each visit.

The software captures three main types of data. First, it records the DOM, which describes the structure and current state of each page. Second, it logs user events, such as clicks, scrolls, form inputs, and navigation actions. Third, it collects metadata including timestamps, device details, viewport size, and browser information.

During playback, session replay tools rebuild the session by applying recorded events and DOM changes in chronological order. The result shows exactly what the user saw and did, based on structured data rather than video files.

Session recording vs. session replay

These terms are often used interchangeably, but they describe different parts of the same process:

• Session recording: The data collection phase that captures raw interaction data, DOM snapshots, and metadata during a user’s visit
• Session replay: The reconstruction phase that turns recorded data into visual playbacks you can watch and analyze

Session recording focuses on gathering information, while session replay focuses on making that information viewable and actionable.

Web and mobile session replays

Web session replay captures DOM changes, user inputs, clicks, scrolls, URL changes, viewport resizing, and network requests. It reconstructs pages and interactions in sequence, including single-page app updates and dynamic content changes.

Mobile session replay records view hierarchy changes, touch interactions, gestures, screen orientation shifts, and app lifecycle events. It aligns these events with UI state changes to reproduce the in-app experience without filming the actual screen.

During playback, session replay tools rebuild the session by applying recorded events and DOM changes in chronological order. The result shows exactly what the user saw and did, based on structured data rather than video files.

Session replay follows a three-step process: data collection, reconstruction, and playback. Each step transforms raw user interactions into a clear, reviewable sequence of events.

During data collection, the system captures the page’s initial structure through a DOM snapshot, then tracks small changes (or mutations) as the page updates. It also logs every user action with precise timestamps and contextual information.

The reconstruction phase organizes all captured data on a timeline. The system rebuilds the initial screen state, then applies each change in chronological order, including route changes in single-page applications and dynamic content updates.

Playback renders the reconstructed pages and applies user interactions at the correct moments. The timeline moves cursors, scrolls pages, and highlights interactions to match the original sequence exactly.

DOM events and user interactions

Session replay captures specific types of events that define the :

• Mouse movements: Cursor tracking, click locations, and hover states
• Keyboard inputs: Form submissions and text entry, with sensitive data automatically masked
• Page interactions: Scrolling behavior, navigation patterns, and element changes
• Browser context: Device type, screen resolution, viewport size, and session timing

These events are timestamped and stored with enough detail to recreate the exact sequence during playback.

Performance impact on websites

Modern session replay tools minimize impact on site speed through several techniques. Lightweight instrumentation collects structured data rather than heavy assets or video files. Data compression reduces payload sizes, and batching sends events in groups rather than individually.

Many implementations utilize background processing and upload data during idle periods or when stable network connections are available. These approaches reduce main-thread work, helping to maintain smooth scrolling and responsive user interactions.

Session replay provides direct visibility into real user interactions, which can accelerate analysis for product, design, engineering, and support teams. The same depth of data also introduces considerations around privacy, performance, and storage costs.

Session replays reveal behavior patterns that aggregate metrics often miss, like repeated clicks on broken elements or confusion during checkout flows. However, individual sessions can overrepresent edge cases if viewed without broader context.

Identify user experience friction

Session replays surface struggle signals that traditional analytics can’t detect. These include repeated clicks on non-interactive elements, rapid back-and-forth navigation, excessive scrolling to find content, and extended pauses on forms or checkout steps.

These behavioral patterns reveal interface problems, unclear labels, and confusing workflows more clearly than bounce rates or alone.

Debug errors with full context

Engineers use session replays to trace the exact sequence leading to errors. They can see which pages users visited, elements they clicked, fields they changed, and API calls that triggered problems. Environmental details like browser type, device specifications, and network conditions help isolate root causes.

This context enables consistent bug reproduction and reduces time spent interpreting vague error reports.

Consider storage and privacy costs

Session replay data grows with , DOM complexity, and interaction volume, affecting storage and bandwidth costs. Common management approaches include event sampling, data compression, and tiered policies that strike a balance between cost and analytical value.

Privacy considerations require careful data masking, user consent management, and compliance with regulations like GDPR and CCPA.

Effective evaluation covers three main areas: scalability for high-traffic sites, usability for finding relevant sessions quickly, and integration capabilities with existing analytics and .

Key technical considerations include capture accuracy across different browsers and devices, data retention policies, and API access for programmatic analysis and automation.

Search and filtering capabilities

Large session datasets require robust search functionality to find specific interactions. Effective session replay tools offer filtering by user attributes, page URLs, specific events, error conditions, and custom metadata.

Advanced features include saved searches, automated alerts for error patterns, and that connects sessions to broader user segments.

Integration with analytics platforms

Session replay gains value when connected to existing . Look for tools that integrate with analytics platforms, , and customer support workflows.

Key integration points include user identity resolution across devices, experiment context for , and direct links from error tracking to relevant session replays.

Amplitude Session Replay integrates directly with Amplitude Analytics, using the same data collection and user identification systems. This unified approach eliminates the need for separate tracking implementations while maintaining consistent and .

The integration enables immediate connections between session replays and existing , cohorts, and without additional configuration.

One-click setup within Analytics

Session replay activates from within your existing Amplitude workspace without installing a separate tracking code. It uses your current implementation to capture interactions while respecting existing privacy settings and data masking rules.

Configuration options appear alongside your analytics settings, making it simple to adjust , retention periods, and capture preferences.

AI-powered session insights

Amplitude AI automatically scans incoming sessions to identify notable patterns like error sequences, unusual navigation, and conversion barriers. It generates summaries highlighting key events and environmental factors for faster triage.

These automated insights help teams prioritize which sessions to review first, focusing attention on the most impactful user experiences.

Amplitude’s connects session replay with analytics, experimentation, and personalization in a unified workspace. Teams can analyze behavior, test hypotheses, and activate insights without moving data between separate systems.

The platform maintains consistent user identification, event definitions, and privacy controls across all features, ensuring session replay data aligns with broader product analytics and experimentation results.