GCLID (Google Click ID)
A unique tag Google appends to every ad click's URL. It lets a later conversion be matched back to the exact ad, keyword, and auction.
Free · no signup · last reviewed August 29, 2026
The definition
A unique tag Google appends to every ad click's URL. It lets a later conversion be matched back to the exact ad, keyword, and auction.
Why it matters to an owner
If your forms store the gclid, you can prove which keyword produced which customer — the difference between guessing and knowing.
This is the work. Want it done?
Everything here is free to use yourself — that’s the point. If you’d rather a senior marketer just handle it, in your accounts and your name: 20-minute call, no pitch deck.