Convert text to 1337. Basic (vowels) or full (all common substitutions).
Leetspeak (or 1337) replaces letters with similar-looking numbers and symbols, an internet subculture style from gaming and hacker forums. 'elite' becomes '31173'.
Basic only swaps the vowels a, e, i, o (so it stays readable). Full also swaps consonants like s to 5, t to 7 and b to 8 for the heavier classic look.
Yes, runs entirely in your browser.