alert(1) to win
Call alert(1) through unsafe code with the shortest input you can find
alert(1) to win is a series of XSS puzzles. Each level shows you a small function that builds HTML from your input in an unsafe way. You type an input that breaks out and calls alert(1), and the page shows the output so you can see whether you won.
Free · No login · Browser · Advanced
About alert(1) to win
The twist is golf scoring: the shortest input wins. That pushes you to learn odd corners of HTML and JavaScript parsing, so it suits people who already know XSS basics. The creator marks it as old, and some score boards are closed.
It runs in the browser with no account. To keep your progress or move to another browser, you bookmark a save link.
On Breakpoint since 23 Oct 2026.