utm_source?The oldest and most common tracking tags on the web: labels that tell the site's analytics which campaign, email or ad brought you there.
This page covers the whole family: utm_source, utm_medium, utm_campaign, utm_term, utm_content, utm_id, and the newer GA4 additions utm_source_platform, utm_creative_format and utm_marketing_tactic.
UTM stands for Urchin Tracking Module, after Urchin, the analytics company Google bought in 2005 and turned into Google Analytics. The five classic parameters label where a visit came from: the source (which site or list), the medium (email, banner, social), the campaign name, the search term, and which specific button or variant was clicked.
They are not unique identifiers by themselves; two people clicking the same newsletter link carry identical tags. What they leak is context. A URL you paste into a group chat can quietly announce that you found it in a marketing email, which list you are on, and which promotion hooked you. Combined with other parameters or with analytics cookies on the destination site, that context gets folded into your profile there.
Because they are free-form text, senders can and do abuse them. Some newsletters put a subscriber token straight into utm_content or utm_campaign, which turns a harmless-looking label into a personal identifier.
Always. UTM tags exist only for the destination site's analytics; nothing on the page reads them to render content. Deleting everything from utm_source through the last utm_ parameter changes what the site's marketing team sees in a report, and nothing else.
Rather's Link Shortener strips utm_source and hundreds of parameters like it, right in the address bar and in everything you copy or share. Free, open source, no account, no data collection, and the page you are on never breaks: the cleanup happens after the site has already loaded.