Tiny Tools › URL parameter glossary › _kx
_kxAdded by Klaviyo to the links inside its marketing emails. The _kx value is an encoded "exchange ID" that identifies you — the specific subscriber whose profile the email was sent to — so a click can be tied back to your record and used to build your on-site tracking session. Like Mailchimp's mc_eid, it can de-anonymise whoever opens the link, so it's worth stripping before you paste an email link anywhere public.
Safe to remove? Yes. _kx is used for tracking and reporting only — deleting it does not change the page you land on. Strip it before sharing a link to keep it clean and private.