In order to produce the link preview, probably. As far as why it's character by character, I don't know, but that doesn't seem very sinister to me. Checking URLs letter by letter is sloppy, especially if you're not even trying to do auto completion, but it doesn't reveal any more information than a complete url could. Anyway, I would think they are expecting people to paste URLs in, not type them.<p>I've written code to fetch sites and give a preview, for a bookmarking bookmarklet. This involves analyzing the html for title and to select best image to represent the page. That of course necessitates retrieving the page, either through the client or server.