Reading Requests In DevTools

Tag Assistant tells you a tag fired; the Network tab in Chrome DevTools tells you what was actually sent on the wire. This is the layer most marketers never open, and it settles arguments instantly.

Find the GA4 hit

• Open DevTools (F12) → Network tab.
• Filter by collect (GA4 sends to /g/collect).
• Click a request and read the Payload / query parameters.

# Key GA4 parameters in a /g/collect request
en   = purchase        # event name
ep.* = event params (strings)   e.g. ep.coupon=SAVE10
epn.*= event params (numbers)   e.g. epn.value=129
tid  = G-XXXXXXX       # measurement id
cid  = client id

What it reveals

• A value sent as a string when it should be a number (look for ep.value vs epn.value).
• A missing parameter the tag was supposed to include.
• Duplicate requests, the smoking gun for double-counting.
• Whether the hit went to Google or (server-side) to your own tagging URL.