Somebody links you a post on X and the site demands an account to read it. XCancel is a running instance of Nitter, the open-source front end that fetches the page server-side and hands you plain HTML — no JavaScript, no ads, and no request from your browser to Twitter at all, so there is nothing to fingerprint. Profiles come with RSS feeds, which quietly makes X readable from a feed reader again. AGPLv3.