What is the _rdt_uuid cookie?
This cookie is set by Reddit and is used for remarketing on reddit.com.
Our October 2026 scan found it on 46 sites (2% of the 2,450 we scanned), set before any consent.
- Purpose
- Advertising
- Belongs to
- Set as
- First-party (under the site's own domain)
- Typical lifetime
- 3 months (vendor says: 90 days) — about what the vendor documents
Sites that set _rdt_uuid before consent
The highest-ranked 30 of 46 sites.
- yuga.com5 tracking companies
- applovin.com8 tracking companies
- mediatek.com7 tracking companies
- optimizely.com4 tracking companies
- oxylabs.io11 tracking companies
- curseforge.com9 tracking companies
- usps.com24 tracking companies
- tailscale.com7 tracking companies
- character.ai5 tracking companies
- bidmachine.io13 tracking companies
Show 20 more sites
- instructure.com17 tracking companies
- primis.tech11 tracking companies
- verizon.com20 tracking companies
- adp.com6 tracking companies
- scmp.com17 tracking companies
- technologyreview.com6 tracking companies
- redis.io12 tracking companies
- simplisafe.com31 tracking companies
- utah.edu11 tracking companies
- libsyn.com8 tracking companies
- gm.com10 tracking companies
- xero.com18 tracking companies
- sfu.ca8 tracking companies
- vt.edu10 tracking companies
- alchemer.com13 tracking companies
- domain.com6 tracking companies
- thedailybeast.com18 tracking companies
- gitbook.io7 tracking companies
- tufts.edu12 tracking companies
- huntington.com9 tracking companies
How to stop it
Declining non-essential cookies in a site's consent banner should stop _rdt_uuid 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.