What is the c cookie?
Records anonymous user data, such as IP, geographical location, websites visited and ads clicked on, in order to optimise visualisation of ads according to user movement around websites using the same advertising network.
Our October 2026 scan found it on 57 sites (2% of the 2,450 we scanned), set before any consent.
- Purpose
- Advertising
- Belongs to
- Magnite
- Set as
- First-party on 4% of sites, third-party on 96%
- Typical lifetime
- 12 months (vendor says: 1 month) — longer than the vendor documents
Sites that set c before consent
The highest-ranked 30 of 57 sites.
- amazon.com33 tracking companies
- namecheap.com4 tracking companies
- alibaba.com7 tracking companies
- dell.com12 tracking companies
- globo.com24 tracking companies
- amazon.co.za32 tracking companies
- wp.pl1 tracking company
- livejournal.com11 tracking companies
- amazon.com.mx34 tracking companies
- olx.com.br10 tracking companies
Show 20 more sites
- terra.com.br23 tracking companies
- hotpepper.jp13 tracking companies
- dmm.co.jp5 tracking companies
- vnexpress.net14 tracking companies
- jalan.net27 tracking companies
- tenki.jp27 tracking companies
- oricon.co.jp36 tracking companies
- haberler.com14 tracking companies
- syosetu.com24 tracking companies
- carsensor.net31 tracking companies
- 24h.com.vn20 tracking companies
- immobiliare.it6 tracking companies
- goodreturns.in25 tracking companies
- kakuyomu.jp18 tracking companies
- chordtela.com34 tracking companies
- rambler.ru9 tracking companies
- animanch.com22 tracking companies
- politico.com31 tracking companies
- hatena.ne.jp19 tracking companies
- scmp.com17 tracking companies
Related cookies
Other cookies from Magnite.
How to stop it
Declining non-essential cookies in a site's consent banner should stop c being set on later visits. Blocking third-party cookies in your browser settings stops the third-party kind everywhere, and clearing cookies for a site removes any it already set.
Description from the Open Cookie Database (Apache 2.0).
Understanding this page
- How cookie lifetimes work, and why a 13-month _ga matters
What a cookie's "expires" field actually controls, why Google Analytics ships a 2-year default that many sites cut down to 13 months, and how Safari's 7-day cap on script-set cookies changes the picture.
- First-party vs third-party cookies (and why "first-party" still tracks you)
What the distinction actually means technically, why browsers only block one of the two, and how CNAME cloaking, server-side tagging and cookies like _ga let sites keep tracking under their own domain.
- How to block or limit trackers
Browser privacy settings, content blockers, Global Privacy Control and clearing cookies compared honestly — what each one actually stops, what it doesn't, and what it costs you in return.