Leetspeak Converter

Turn text into 1337 (leetspeak), with basic or advanced letter swaps.

Level

Input

Leetspeak Output

Characters: 0

What is leetspeak?

Leetspeak (“1337”, from “elite”) is an internet slang that swaps letters for visually similar numbers and symbols — A becomes 4, E becomes 3, O becomes 0. It started in early bulletin-board and gaming culture. The basic level uses the most common substitutions for readable text, while advanced swaps more letters for a denser, hacker-style look. Conversion runs entirely in your browser.

Built and maintained by Meet Shah · Last updated 5 August 2026

What this tool is used for

Producing a stylised handle or tag for a game or a forum.
Comparing the basic and advanced spellings of a name before settling on one.
Checking whether a word filter catches the fully substituted spelling of a word.
Producing input for a password-strength demonstration.
Setting a puzzle whose answer is an obscured word.

How it works in practice

A worked example

A gamer wants a stylised handle built from the name Cobalt Ghost and runs it through both levels to compare the spellings before settling on one.

Input

Cobalt Ghost

Output

Basic      C0b4l7 Gh057
Advanced   (084|7 6h057

Advanced is basic plus five more letters: every basic swap is kept, and b, c, g, l and z gain replacements of their own, which is why Cobalt becomes C0b4l7 at one level and (084|7 at the other. Letters are looked up regardless of case, so the capital C and G turn into ( and 6 at the advanced level, while the basic level, which has no entry for either, passes them through with their capitals intact. Every substitution trades one character for one character, so both spellings stay twelve characters long, the same as the name typed in, as the Characters count under the output shows.

The edge case that catches people

Advanced brings in the only two replacements that are neither letters nor digits, ( for c and | for l, and this name contains both. That matters wherever a name has to pass a character whitelist. Discord, for one, limits usernames to lower-case a to z, the digits 0 to 9, the period and the underscore, so it would refuse the bracket and the bar, and the space as well. For a username there, start from the basic spelling, lower-case it and swap the space for an underscore, which gives c0b4l7_gh057.

When not to use this tool

There is no decoding direction, so it cannot turn leetspeak back into plain text: paste C0b4l7 Gh057 back in and the basic level returns it unchanged, while the advanced level converts it a second time into (084|7 6h057. It is also a thin source of test cases for a word filter. Each level applies every substitution it knows at once and offers a single spelling, so password comes out as p455w0rd at both levels, and a partial swap such as p4ssword, which a filter has to catch as well, never appears.

Frequently Asked Questions

What is leetspeak?: A substitution of letters for visually similar numbers and symbols — 3 for E, 4 or @ for A, 1 or ! for I, 0 for O, 7 for T. It emerged on 1980s bulletin boards, partly as an in-group marker and partly to evade keyword filters.
Why does 'leet' mean elite?: It is a clipping of 'elite', originally referring to users with privileged BBS access. '31337' — leet for 'eleet' — became the canonical example, and survives as port 31337 in various pieces of software.
Does leetspeak make a password stronger?: Barely. Password crackers have applied leet substitution rules for decades, so 'P@ssw0rd' falls almost as fast as 'password'. Length and unpredictability are what matter; predictable substitution adds close to nothing.
Are there different intensity levels?: Here there are two. Basic swaps six letters, a, e, i, o, s and t, for 4, 3, 1, 0, 5 and 7, and stays readable. Advanced adds b, c, g, l and z, as 8, (, 6, | and 2, which reads more like code. Both swap one character for one, so the text keeps its length.
Does it still defeat content filters?: Rarely. Modern moderation normalises leet substitutions before matching, and does so precisely because the technique was so widespread. It persists now mostly as style and nostalgia.
Does it survive a copy into a plain-text field?: Yes — the substitutions are ordinary ASCII digits and punctuation, not styled Unicode, so the text is identical everywhere. That is what separates it from the fancy-text generators, whose output depends on font coverage.
Can leetspeak be reversed reliably?: Not unambiguously. 1 could be i or l, and 5 could be s or a real digit, so decoding needs a dictionary and still guesses. The mapping is deliberately many-to-one.
Why did it emerge?: On 1980s bulletin boards, partly as an in-group marker and partly to evade keyword filters watching for particular words. Both purposes are historical now — the filters read substitutions, and the style survives as a joke.

Common errors and gotchas

Using leet substitutions in a password and believing it adds strength, since crackers try them first.
Assuming one substitution table, as they vary widely by community.
Expecting search to find the converted text, which no longer matches the word.
Using it in a display name that becomes unreadable to a screen reader.
Treating it as obfuscation with any security value at all.