The least typeable URL on this list
news.ycombinator.com/user?id=yourname is a question mark, an equals sign and a domain most people spell wrong on the first try. It is, in other words, the perfect candidate for a QR code — there is no realistic scenario where someone types it off a badge correctly.
The audience makes it worth doing. HN usernames carry weight at hackathons, founder events and technical meetups, where "I'm the one who wrote that comment" is a real introduction. A code on a badge or a slide turns that into a profile someone can actually open.
Keep it minimal. HN is a plain site and a plain code suits it: black, square modules, no logo. It's also the most reliable combination for a small badge print, which is where these usually end up.
Everything happens in your browser. The QR encoder is built into this page, so your username is never sent to a server, nothing is logged, and there's no daily limit. The code is static — the link lives in the pattern itself, with no redirect service in the middle that can expire, start charging or go down.