How to convert text to leetspeak
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- Pick a direction. Auto-detect decodes when more than 15% of the characters look like substitutes, and encodes otherwise.
- Pick a substitution set. Conservative replaces six letters, and Aggressive replaces more.
- Choose Custom to write your own rules, one per line, such as
s=5,$. - Copy the result or download it as a .txt file.
Substitution sets
Leetspeak swaps letters for look-alike digits and symbols. The Conservative set maps a to 4, e to 3, i to 1, o to 0, s to 5 and t to 7, so "leet" becomes l337.
The Aggressive set also changes b, c, g, h, l, z and uses symbols such as #, ( and $. When a letter has several substitutes, encoding uses the first one listed.
Decoding is a best guess
Several characters stand for more than one letter. A 1 can be an i or an l, and in the Aggressive set | and ! overlap as well. The decoder picks one reading and lists every ambiguous character under the result, with the letters it could have been.
Upper and lower case are not kept when encoding, because digits and symbols have no case. Letters without a substitute and all punctuation pass through unchanged.
Frequently asked questions
What is leetspeak?
Leetspeak is a way of writing in which letters are replaced by digits or symbols that look similar, such as 3 for e and 0 for o. It started in online communities and is now used for usernames, passwords and style.
Can leetspeak be decoded exactly?
Not always. Characters such as 1 can stand for more than one letter, so the decoder chooses one and flags the character as ambiguous. Context from the surrounding word is the only way to be sure.
Is the case of letters kept?
No. Digits and symbols have no case, so upper-case and lower-case letters with a substitute give the same result. Letters without a substitute keep their original case.
Can I define my own substitutions?
Yes. Choose Custom and enter one rule per line, with the letter, an equals sign and one or more substitutes separated by commas. The first substitute is used for encoding, and all of them are recognised when decoding.
Is my text uploaded?
No. The conversion runs in your browser and the text is not sent anywhere.