Sampling and Event-Triggered Recording

Recording every session is expensive and rarely necessary. sampleRate and alwaysRecordEvents let you record a small slice of traffic but still guarantee coverage on the sessions that matter.

sampleRate

sampleRate is a number between 0 and 1 that controls what fraction of sessions are recorded.

• 1 (default) — record every session
• 0.1 — record 10% of sessions
• 0 — never auto-record (you can still promote sessions via alwaysRecordEvents)

The sampling decision is made once per session and is sticky for the rest of the session lifetime — a session is either in or out, it doesn't flip mid-flight from random sampling.

ours('init', '{cdp_token}', {
  session_replay: {
    token: 'replay_token',
    sampleRate: 0.1,
  },
});

alwaysRecordEvents

alwaysRecordEvents is a list of event names that override sampling. When a track event with a matching name fires during a session that was sampled out, recording starts immediately from that point forward.

ours('init', '{cdp_token}', {
  session_replay: {
    token: 'replay_token',
    sampleRate: 0.1,
    alwaysRecordEvents: ['checkout', 'purchase', 'error'],
  },
});

Note: The Ours Privacy Web SDK automatically notifies Session Replay whenever a track event fires, so event-triggered recording works without any additional code on your part.

What gets captured when an event triggers recording

Recording starts at the moment the event fires — events and DOM activity that happened before the trigger are not retroactively captured. If you need to capture the lead-up to a promotion event, set sampleRate higher (e.g., 0.5) and trade off cost for context.

Common patterns

Record 10% of traffic, but always capture checkout and errors

session_replay: {
  token: 'replay_token',
  sampleRate: 0.1,
  alwaysRecordEvents: ['checkout', 'purchase', 'error'],
}

Only record sessions with specific events

session_replay: {
  token: 'replay_token',
  sampleRate: 0,
  alwaysRecordEvents: ['checkout'],
}

This records no sessions by default. Recording starts the moment a checkout event fires. Cheap, targeted, and useful for funnel debugging.

Record everything during a launch, scale back later

session_replay: {
  token: 'replay_token',
  sampleRate: 1, // 100% — flip to 0.1 once you have enough data
  alwaysRecordEvents: ['checkout', 'signup', 'plan_upgrade'],
}

The Web SDK handles replay event notifications and session rotation automatically. You only need to configure sampleRate and alwaysRecordEvents in your session_replay settings.

Next steps

• Configuration — every supported option