Convert text to 1337 speak with 5 intensity levels — from barely-there Basic to extreme multi-character substitutions. Bidirectional: encode normal text to leet or decode leet back to English. Includes a randomise mode and a full character substitution reference table.
Enter any text in the input box. The conversion happens in real time as you type. Use the direction toggle to switch between Normal→Leet (encode) and Leet→Normal (decode).
Select from 5 levels: Basic (E→3, O→0 only, fully readable), Low (adds A→4, S→5, T→7), Medium (adds B→8, G→9, L→1), High (adds multi-character subs like W→\/\/), and Extreme (maximum substitution with rarest patterns like M→|\/|).
Copy the converted text with one click. Toggle Randomise to vary which substitutions are applied so each conversion looks slightly different — useful for generating unique usernames or passwords. The reference table below shows every substitution used at each level.
Leet speak (also written as 1337, l33t, or l33t5p34k) is an alternative alphabet that replaces standard Latin letters with numbers, symbols, and character combinations that look visually similar. It originated in the 1980s on bulletin board systems (BBS) where hackers and elite users used it as a coded language to identify themselves to each other and exclude novices ("noobs"). The word "leet" comes from "elite" — shortened and spelled in the leet style itself as "1337".
The most universally recognised leet substitutions are: A→4, E→3, I→1 or !, O→0, S→5, T→7, B→8, G→9, L→1. More complex substitutions include: W→\/\/, M→|\/|, N→|\|, H→|-|, K→|<, X→><, and many others. The substitutions chosen depend on the intensity level — lower levels use only the most recognisable simple substitutions; higher levels use rarer multi-character patterns.
Switch to Decode mode using the direction toggle. The decoder reverses the substitution map — it identifies multi-character leet sequences first (longer patterns take priority) before single-character substitutions. This prevents ambiguous patterns from being decoded incorrectly. For example, |\/| is decoded as M before individual characters are processed.
Basic: only E→3 and O→0. The text remains easily readable by anyone. Low: adds A→4, S→5, T→7. Still very readable. Medium: adds B→8, G→9, L→1, I→!. Moderately obscured. High: adds W→\/\/, V→\/, U→(_), and other two-character substitutions. Requires familiarity to read. Extreme: uses the rarest multi-character patterns like M→|\/|, N→|\|, K→|<. Very difficult to read without practice.
Yes, though its purpose has evolved. In the 2000s it spread from hacker circles to mainstream gaming, IRC, and Usenet. Terms like "n00b", "pwned", and "h4x0r" crossed into mainstream culture. Today it is used playfully and nostalgically — as a nod to early internet culture. Gamers use it for usernames (Sl4y3r, D3stroy3r), and it appears in memes, usernames, and internet humour. It is also sometimes used for simple password obfuscation, though this provides minimal security.
Leet substitutions like p@ssw0rd or s3cur!ty are well-known patterns that password crackers test specifically. Dictionary attacks include leet variants of common words, so simple leet substitutions add very little security. For strong passwords, use a random combination of uppercase, lowercase, digits, and symbols rather than a leet version of a real word.
