Leet speak, or 1337, is an internet writing style that replaces letters with visually similar numbers and symbols. Level 1 uses only the most common substitutions, keeping the text easy to read.

Which substitutions does Level 1 use?

The basic set: A becomes 4, E becomes 3, I becomes 1, O becomes 0, S becomes 5 and T becomes 7. All other characters are left unchanged.

Is it case sensitive?

No. Both uppercase and lowercase letters are substituted, since the digits have no case. Letters not in the substitution set keep their original case.

Can I decode leet back to normal text?

Yes. Decode mode reverses the substitutions, turning 3 back to e, 4 to a, and so on. Digits that were genuinely meant as numbers will also be converted, so use decode on leet text only.

Is my text uploaded anywhere?

No. The conversion runs entirely in your browser and nothing is sent to a server.

Leet Speak Level 1 — Gera Tools

Leet speak (from “elite”, written 1337) is an internet writing style that swaps letters for look-alike numbers and symbols. It grew out of 1980s bulletin-board and gaming culture. Level 1 is the gentlest variant: it uses only the handful of substitutions that stay easy to read, which makes it popular for usernames, gamer tags and casual chat.

How it works

The Level 1 mapping replaces six letters with the digits they resemble:

A -> 4    E -> 3    I -> 1
O -> 0    S -> 5    T -> 7

Encoding scans the text and substitutes each of these letters (in either case) with its digit, leaving every other character — other letters, spaces, punctuation — untouched. Because the swapped digits have no case, capitalisation is only preserved on the letters that are not substituted.

Decoding reverses the table: each 4 3 1 0 5 7 becomes a e i o s t. Since decoding cannot tell a deliberate number from a substituted letter, run it only on text you know is leet.

Example

The word ELITE becomes 3L173: E to 3, L stays, I to 1, T to 7, E to 3. The greeting leetspeak turns into l337sp34k. Decoding l337 returns leet.