Debug FullStory in Chrome DevTools

What FullStory traffic looks like

FullStory loads a recording script, then ships session capture as compressed bundle uploads, readable only around the edges.

Endpoint pattern

Recording script from edge.fullstory.com/s/fs.js (historically fullstory.com/s/fs.js; European tenants use an eu1.fullstory.com edge); capture goes to rs.fullstory.com on /rec/... paths: /rec/page registers the page, then recurring /rec/bundle uploads follow

Transport

Batched POSTs; bundles carry compressed DOM snapshots, mutations, and interaction data. You will not read individual clicks out of them, but their cadence tells you capture is live

Key parameters

Org ID, set in the _fs_org window global by the snippet and repeated in the /rec/ query strings · session and page IDs that stitch bundles into one replay

Payload

Custom events and identify calls made through the FS() API (FS('trackEvent', ...), FS('setIdentity', ...)) ride the same ingestion channel rather than appearing as individually readable analytics hits

Debugging FullStory with Event Watcher

• No dedicated parser: requests are identified by hostname, labeled with the platform name and Session Replay category badge, and shown with parsed query parameters, body, and the per-event Cookies section.
• That answers the recurring questions: is fs.js loading, which org ID is it recording into (read it from the /rec/ query strings), and are bundles actually uploading?
• Consent timing per request shows whether capture started before or after the CMP resolved.
• Grouping by Endpoint separates the script load from the rs.fullstory.com ingestion traffic.

FullStory and consent

Event Watcher checks FullStory against analytics consent. FullStory's own consent controls work at the element and user level: FS('setIdentity') and consent APIs decide what gets captured.

None of that is visible on the wire. What you can verify externally is whether recording traffic exists before the CMP resolved.

A /rec/page request and bundle uploads before the banner interaction are marked pre-consent and counted by the violations counter.

Because replay captures rendered content, treat a pre-consent bundle as a priority finding: real user behavior was uploaded before permission, regardless of what masking rules apply inside the recording.

Common debugging scenarios

• Sessions missing from FullStory. Confirm fs.js loads and /rec/bundle uploads follow. A page with the script but no bundles points at sampling, a blocked domain configuration, or a crashed recorder.
• Recording into the wrong org. Read the org ID from the /rec/ query parameters and compare against the workspace you expect. Staging snippets in production containers are a classic.
• Capture before consent. Check the consent state on the first rs.fullstory.com event of the session.
• Replay splits mid-session. Compare session identifiers across consecutive bundle uploads; a change indicates the recorder restarted.
• Who loaded FullStory? Use the Script Tree view. Snippets pasted into a tag manager by a past vendor engagement are a common surprise during a tracking audit.