Debug Google Analytics 4 in Chrome DevTools

What GA4 traffic looks like

GA4 sends hits to /g/collect, with two first-party shapes that catch people out. Both are still GA4.

Endpoint pattern

google-analytics.com/g/collect, regional siblings like region1.google-analytics.com/g/collect, stats.g.doubleclick.net/g/collect (Google signals on), and google.com/ccm/collect?…tid=G- (server-side / Consent Mode first-party path)

Transport

GET with everything in the query string for small hits; POST for larger ones, with batched events as newline-separated event lines in the body

Key parameters

tid measurement ID (G-XXXXXXX) · en event name (page_view, purchase, custom) · cid / sid / _s client ID, session ID, hit sequence · ep.* / epn.* string and numeric event parameters · up.* user properties

Consent signals

gcs, gcd, dma: Google Consent Mode state; gcs=G100 means denied, G111 granted

E-commerce

pr1, pr2, and so on: one item per parameter, with id, nm, pr, qt fields packed into each value

Debugging GA4 with Event Watcher

• Matches every endpoint variant above, including the regional and /ccm/collect first-party shapes.
• The GA4 parser splits each hit into readable groups: Event, E-Commerce, Session, User Identity, Campaign / Attribution, Consent, Advertising, Page / Document, and Client Hints.
• Batched POST bodies unpack into individual events: a single request carrying five events shows as five entries you can inspect separately.
• Grouped view pivoted by Event Name is a quick way to compare ep.* payloads across repeated events.

GA4 and consent

The extension checks GA4 against analytics consent. GA4 is the canonical Consent Mode platform: with advanced Consent Mode, hits legitimately fire before the CMP answers, but as cookieless pings carrying gcs=G100.

Worst case is the safe case: Event Watcher reads both the CMP's state and the gcs/gcd signals, so only a hit with full cookies before the user chose is flagged as a genuine violation.

See GA4 fires before consent and debugging Consent Mode v2.

Common debugging scenarios

• purchase fires twice. Pivot Grouped view by Event Name and compare the two hits' _s sequence numbers and session IDs: double tag or page reload.
• Wrong measurement ID on one page. Filter to GA4 and scan tid per hit; agency and site-owner streams often overlap.
• Items missing from e-commerce reports. The E-Commerce section of the parsed hit shows whether pr1…prN are present and complete on the wire, before you blame the report.
• A dataLayer event never becomes a GA4 hit. Confirm the push happened via which script pushed this dataLayer event, then check for a /g/collect hit with the matching en.
• Consent Mode pings mistaken for tracking. The Consent section shows gcs per hit. Check it before flagging a violation.