id5-sync.com across 75 measured sites
id5-sync.com is a hostname that appears in the network log of ad-funded publisher pages. This index has no vendor entry for it — no company name, no category, no tracking classification — so everything below is about where it was seen and what the pages around it look like. It was found on 75 of the 5,294 sites measured. Those pages are among the busiest in the index, they are overwhelmingly newspapers and portals outside the United States, and 53 of them run the advertising industry's own consent framework.
Busy pages, by any of the three measures
The median site carrying id5-sync.com contacted 15 separate companies across 78 requests, 4 of them classified as tracking. Among the 88 companies in this index that is rank 14 on companies, rank 12 on requests and rank 16 on trackers. The median count of companies arriving before a consent choice could have been recorded is 11, rank 8 of 88, level with eight others.
elmundo.es is the extreme of the set: 38 companies contacted, 34 of them inside that window, first contact 683 ms, behind an IAB TCF consent tool. mundodeportivo.com: 21 companies, 19 early. goodreturns.in: 21 companies, 19 early, first contact 307 ms. index.hr: 16 and 16, at 492 ms.
Nine of ten had a banner, and most ran the industry's own
64 of the 75 sites carried a consent tool the crawl could detect. An IAB TCF consent tool was seen alongside on 53 of them, OneTrust on 7, Cookiebot on 2, Usercentrics on 1 and Iubenda on 1. A site can carry more than one banner and each recognised tool is counted separately, so those figures should not be read as slices of the 64.
The concentration matters. The IAB TCF framework was designed to carry consent signals between advertising businesses in a machine-readable form. A publisher that installs it is not an accidental participant in the advertising market; it is a deliberate one. This is a set of sites that built the plumbing.
A split between two kinds of publisher
The European examples front-load almost everything. buzzfeed.com contacted 15 companies with all 15 inside the window, first contact 422 ms, behind a OneTrust banner. index.hr, elmundo.es and mundodeportivo.com behave the same way, with 16 of 16, 34 of 38 and 19 of 21 respectively.
The East Asian examples do not. donga.com contacted 11 companies with none of them inside the window, first contact at 3556 ms — the longest single first contact in this entry by a wide margin. ppomppu.co.kr: 13 companies, 1 early, at 1799 ms, behind an IAB TCF tool. netkeiba.com: 21 companies, 3 early, at 1403 ms, also behind an IAB TCF tool.
Those three pages carry as much third-party weight as the European ones. They simply do not open it at the start of the load.
Which is why the early-contact share is low here
63 of the 75 sites had at least one company contacted before a consent choice could have been recorded — 84 percent, rank 83 of the 88 companies in this index. Twelve sites had none at all, and the examples above show what those look like.
The median count of companies arriving after the window closes is 4, which is high for this index and consistent with the same picture: on a typical page in this set, a meaningful share of the stack is still arriving later. Median first contact was 683 ms, rank 40 of 88, sitting between the two clusters rather than describing either.
id5-sync.com was present on those 63 sites where early contact happened. The crawl records the count per site and not the identity of the companies inside the window, so nothing here places this host among them.
It travels with a regional twin, and with the exchanges
Google was present on 69 of the 75 sites, 92 percent. Amazon Ads on 43, 57.3 percent. crwdcntrl.net on 41, 54.7 percent. fastclick.net on 34, 45.3 percent. Comscore on 20 and Criteo on 19. Meta Pixel and jsDelivr on 13 each, and hadronid.net on 10.
The entry that stands out is eu-1-id5-sync.com, on 27 of the 75 sites — 36 percent. A near-identical hostname with a regional prefix, appearing on a third of the same pages, is the signature of a service that routes some traffic separately by region. The crawl records the co-presence and the rate; it does not establish ownership, and this page will not assert one.
| Site | Companies | Before consent | First contact |
|---|---|---|---|
| soundcloud.com | 15 | 11 | 228 ms |
| speedtest.net | 11 | 9 | 684 ms |
| allaboutcookies.org | 11 | 7 | 915 ms |
| elmundo.es | 38 | 34 | 683 ms |
| donga.com | 11 | 0 | 3556 ms |
| mundodeportivo.com | 21 | 19 | 671 ms |
| buzzfeed.com | 15 | 15 | 422 ms |
| netkeiba.com | 21 | 3 | 1403 ms |
| index.hr | 16 | 16 | 492 ms |
| goodreturns.in | 21 | 19 | 307 ms |
| ppomppu.co.kr | 13 | 1 | 1799 ms |
| sinoptik.ua | 18 | 5 | 398 ms |
| Tool | Sites |
|---|---|
| IAB TCF consent tool | 53 |
| OneTrust | 7 |
| Cookiebot | 2 |
| Usercentrics | 1 |
| Iubenda | 1 |
Seen on the same pages
Companies most often contacted by the same sites. Co-presence only — the crawl records what arrived, not who called whom.
- GoogleTogether on 69 of these sites
- Amazon AdsTogether on 43 of these sites
- crwdcntrl.netTogether on 41 of these sites
- fastclick.netTogether on 34 of these sites
- ComscoreTogether on 20 of these sites
- CriteoTogether on 19 of these sites
- jsDelivrTogether on 13 of these sites
- Meta PixelTogether on 13 of these sites
Questions
What is id5-sync.com?
A hostname with no entry in this index's vendor catalogue. What is measured: it appeared on 75 of 5,294 sites, almost all of them ad-funded publishers, with Google on 92 percent of those pages and Amazon Ads on 57.3 percent.
Why do so many of these sites run an IAB TCF banner?
53 of the 64 sites with a detectable banner did. That framework passes consent signals between advertising businesses, and the publishers in this set are participants in that market rather than bystanders.
Did it load before consent?
Not answerable from this data. Early contact is recorded per site, not per company. What can be said is that 63 of the 75 sites had some company arrive before a choice could have been recorded, with a median of 11 companies in that window.
Why is the early-contact share lower than most entries here?
84 percent, rank 83 of 88. Twelve sites had none, and the examples with none — donga.com at 3556 ms, ppomppu.co.kr at 1799 ms, netkeiba.com at 1403 ms — are pages that load their third parties late rather than pages that load few.
What is eu-1-id5-sync.com?
A hostname sharing the same distinctive string, present on 27 of the 75 sites, 36 percent. The crawl records that they appear together at that rate and nothing about who runs either.