What is the _im_id.* cookie?
We don't have a vendor description for this cookie yet, but our scan shows it's set under the sites' own domains rather than by a third party, and it typically lasts 13 months. It's listed as unclassified.
Our October 2026 scan found it on 4 sites (0% of the 2,450 we scanned), set before any consent.
- Purpose
- Unclassified
- Set as
- First-party (under the site's own domain)
- Typical lifetime
- 13 months
- Name
- A family of cookies: the part after _im_id. varies by site or account.
Sites that set _im_id.* before consent
The highest-ranked 4 of 4 sites.
- oricon.co.jp36 tracking companies
- gamewith.jp6 tracking companies
- ecnavi.jp7 tracking companies
- asahi.com41 tracking companies
How to stop it
Declining non-essential cookies in a site's consent banner should stop _im_id.* 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.
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.