Inflight corrects a UTM value after it’s already landed in GA4, inside a server-side GTM container. That’s the right layer for it: closest to the source, before the hit is even recorded. It also has a hard prerequisite. If your GA4 setup doesn’t run through server-side GTM, or your team hasn’t migrated yet, there’s no container for Inflight to plug into.
That gap is common, not niche. Plenty of teams still tag campaigns by hand in Google Ads, Meta Ads Manager, or a shared spreadsheet, long before any of it reaches GA4. The naming-convention problem that produces facebook, Facebook, and fb as three unrelated-looking sources doesn’t wait for server-side GTM. It starts the moment someone types a UTM value into a form.
Link Builder handles that earlier moment. It runs the same rule engine Inflight uses at correction time (known values, aliases, composite or “tokenized” fields like utm_campaign built from several parts), but at link-creation time instead: build a link, and it flags a value that doesn’t match your own naming rules before that link is ever pasted into an ad platform. Save the shape of a recurring link as a reusable template, generate a batch of them at once, export the set as CSV.
It has no server-side GTM prerequisite, no product dependency at all, and no limits: no link cap, no plan gate. Unlimited, forever free on every UTM Assistant plan, including Free. If Inflight is the safety net for what still gets through, Link Builder is what keeps more of it from needing the net in the first place.