Using the translator
Type on the left and the substituted text appears on the right. Substitutions picks between the basic set and the wide one.
Basic swaps six letters for digits that resemble them, and the result still reads at a glance. Wide adds symbol clusters like |_| for u and \/\/ for w, and stops being readable almost immediately. Swap the boxes to decode either set.
How the decoding stays honest
Encoding is a lookup. Decoding is harder, because the wide set uses multi-character tokens, and a pass that read one character at a time would turn |_| into three letters rather than one.
So the decoder tries the longest tokens first and only falls back to single characters. That makes it correct for anything this tool produced. Text written by a person is a different matter, since real leetspeak is improvised and nobody uses a fixed table.
Case survives substitution. H and L have no digit in the basic set, so HELLO comes back as H3LL0 rather than being flattened to lowercase.
The six letters that change
Port 31337
Leetspeak grew on bulletin board systems in the 1980s, where it did a job. Boards ran keyword filters on file names and message text, so writing a word with digits in it got the post past the filter. The habit outlived the filters and became a marker of who had been around.
The word itself is "elite", spelled 31337. That number is also a port, and it's the port Back Orifice listened on, the remote administration tool released by the Cult of the Dead Cow at DEF CON in August 1998. Seeing traffic on 31337 was a reliable sign that something had gone wrong on a network, and the joke was that the number said so.
The style is period-specific now. It reads as a deliberate reference rather than as code, which is the usual fate of any writing convention invented to get around a filter.
Related conversions
Pig Latin does the same social job by rearranging sounds instead of swapping characters. Upside-down text and mirror text borrow real characters from other alphabets to change how a word looks.
For text that looks corrupted rather than substituted, zalgo stacks combining marks instead.
Questions
What is leetspeak?
A writing style that replaces letters with digits and symbols they resemble, so "elite" becomes 31337. It started on bulletin boards in the 1980s.
How do I decode leetspeak?
Paste it above and swap the boxes. The decoder handles multi-character tokens correctly, though improvised leetspeak written by a person may not match any fixed table.
Why is 31337 significant?
It spells "eleet" and it's the port Back Orifice used, a remote administration tool released by the Cult of the Dead Cow in 1998. The number became shorthand for an intrusion.
Does leetspeak still get past filters?
Rarely. Modern moderation normalises substitutions before matching, so writing a word in leet is no longer a way around it.