RUM session replay

Session replay records the browser DOM as a full snapshot followed by timestamped incremental changes. MoleSignal reconstructs those events in a sandboxed, non-interactive player. Replay is disabled by default.

Enable sampled replay

const rum = initRum({
  applicationId: 'checkout-web',
  clientToken: 'msrum_your_client_token',
  site: 'https://molesignal.example.com',
  sessionSampleRate: 100,
  sessionReplaySampleRate: 20,
  sessionReplay: {
    blockSelector: '[data-molesignal-block]',
    maskTextSelector: '[data-molesignal-mask]',
    ignoreSelector: '[data-molesignal-ignore]',
  },
});

sessionReplaySampleRate is evaluated only for sessions included by sessionSampleRate. See RUM data sampling for the effective-rate calculation.

Start or stop recording manually

rum.startSessionReplayRecording();

// Stop before a sensitive workflow that should never be recorded.
rum.stopSessionReplayRecording();

Manual start applies only to a session already selected by sessionSampleRate. Starting recording creates a new full DOM snapshot so the replay can be reconstructed.

Recorded events

The recorder captures:

full DOM snapshots and incremental DOM mutations;
pointer movement and clicks;
scrolling and viewport changes;
input interaction with values masked;
stylesheet state and accessible inline styles;
media state supported by rrweb.

A periodic full snapshot is recorded every five minutes by default. Configure a value from 30 seconds through 30 minutes with checkoutInterval:

sessionReplay: {
  checkoutInterval: 5 * 60_000,
},

Privacy controls

All input values are masked. With the default defaultPrivacyLevel: 'mask', all page text is also masked. Define block, mask, and ignore selectors before enabling production replay.

<div data-molesignal-block>Payment details</div>
<span data-molesignal-mask>Customer name</span>
<canvas data-molesignal-ignore></canvas>

Read RUM privacy for selector semantics and a production review checklist.

Optional high-volume capture

The following options are disabled by default because these options can substantially increase payload and storage size:

sessionReplay: {
  collectFonts: false,
  inlineImages: false,
  recordCrossOriginIframes: false,
},

Cross-origin frame recording also requires cooperation from the framed application. Canvas pixels are not replayed by the MoleSignal player. Prefer DOM representations or placeholders for canvas-heavy content.

Transport and retention

Replay uses a separate queue and defaults to a 10-second flush interval with 100 events per batch. Use replayFlushInterval and replayBatchSize to tune client behavior. MoleSignal compresses replay segments in object storage and expires stored segments with the deployment’s compactor.retention_days policy.

Verify replay

Record a non-sensitive test journey

Navigate through multiple pages, click controls, scroll, and trigger one DOM update.

Open the session

Go to RUM → Session replay and open the newly recorded session.

Check reconstruction and masking

Verify the page structure, event timing, progress controls, blocked regions, and masked values.

Check the availability filter

A session appears as replayable only after MoleSignal receives a valid full DOM snapshot.

Data sampling

Estimate replay coverage and volume.

Privacy

Define the recording boundary before rollout.

Getting Started

Observe

Reliability

AI Ops

Data

Collaboration

Admin

Deploy & Operate

Enable sampled replay

Start or stop recording manually

Recorded events

Privacy controls

Optional high-volume capture

Transport and retention

Verify replay

Data sampling

Privacy

​Enable sampled replay

​Start or stop recording manually

​Recorded events

​Privacy controls

​Optional high-volume capture

​Transport and retention

​Verify replay

Data sampling

Privacy

Enable sampled replay

Start or stop recording manually

Recorded events

Privacy controls

Optional high-volume capture

Transport and retention

Verify replay