How Sequential works

• Sequential accepts PostHog, Mixpanel, Amplitude, Pendo, the Smartlook compatibility script and Sequential's own SDK.
• Each SDK sends its events in its own format.
• The key is the project's ingest key. For Pendo, the key is your own Pendo API key.
• Sequential accepts only browser SDKs and PostHog's mobile SDKs.
• Sequential rejects server-side SDKs and HTTP libraries as bot traffic. Examples: posthog-node, curl, axios.

See What each SDK supports.

• The nine classes include Page view, Click, Error, Custom and System.
• If Sequential has no rule for a name, the event becomes Custom. This includes your own events and vendor events that Sequential does not list. For example: PostHog mobile's Application Opened.
• Known vendor housekeeping events become System. For example: page-leave and web-vitals events.
• Sequential stores System events but hides them from event lists by default.

See Events.

• The recorder reads your project's recording settings before it starts.
• On the web, Sequential's own SDK and the Smartlook compatibility script start the recorder for you. They do this when session replay is on for the project.
• With PostHog, Mixpanel, Amplitude or Pendo, the recorder is a separate script tag next to your analytics SDK.
• On mobile, the supported SDK uploads its own recording. See Mobile apps.
• The recorder uses your analytics SDK's session id. Sequential's own SDK gives its id to the recorder automatically.
• If the SDK has no session id, the recorder creates one. The recorder registers it with PostHog, Mixpanel or Pendo, so their events carry it too.
• Matching ids put your events on the replay timeline and in the player's Events tab. See Sessions.

• Sequential sends a short text digest of the session's events, with your rubric, to the judge.
• The judge answers each question with probabilities. Sequential stores these numbers.
• Sequential assembles the sentences you read later from these numbers. The judge writes no prose.

See Judgments.

• If a session has a recording and the judge found a key moment, Watch from m:ss opens the replay there.
• A recorded session without a key moment offers Open replay.
• To check a verdict, open the replay.

• Sequential's SDK sends each event within 5 seconds.
• The recorder uploads as it goes. Sequential prepares the uploads in 5-minute periods. You can play a recording only when all its uploads are ready. Until then, the player shows the time when the recording will be ready, and opens it on its own.
• A verdict in Watch comes no sooner than 30 minutes after the session's last event.
• Sequential checks for sessions every 5 minutes. So the verdict usually comes 30–35 minutes after the last event.
• A verdict takes longer when many sessions wait in the queue. It also takes longer when today's allowance is used up.

• The judge sees page paths, click text, form submits, error messages and your custom events. Each custom event comes with a short summary of its properties.
• The judge compares the outcome with your named milestones. Without custom events, nothing tells it which step of your product mattered. See Send custom events.
• The digest carries page paths without hosts or query strings. It reduces any other full web address to its path.
• The digest shortens labels.
• The digest includes no user id.
• The digest drops custom-event properties with personal-looking names, such as email or phone. See AI and third parties.
• From the recording, the background judge takes only three counts that DevTools measured: JS errors, failed requests and console errors.
• If DevTools did not measure a count, the digest leaves it out. Sequential never sends a missing count as zero. See DevTools in replays.
• In a very long session, the digest can leave out late custom events. See Limits.