Convert plain text to leet speak (1337) and back. Pick a preset intensity, randomize substitutions for that organic hacker-text feel, or fully customize the substitution table below.
Edit any cell to customize. Use commas to separate alternatives; the first one is used unless "Random pick" is enabled. Decoding uses every alternative as a possible source.
"Leet" (or "1337", from "elite") is an alternative alphabet that emerged on early-1980s BBS culture, where users substituted letters with numbers, punctuation, or ASCII art to evade keyword filters and signal in-group status. By the 90s it was a cornerstone of hacker, gaming, and demo-scene culture. Modern leet ranges from light ("h3ll0") to heavy ("|-|3110") and even multi-character forms ("|\|" for N). It's no longer a security technique — it's a stylistic choice and a source of nostalgia, occasionally still useful for obfuscating text in ways that confuse naive automated scanners.