About this tool
The A1Z26 cipher is one of the simplest codes there is: each letter is replaced by its position in the alphabet, so A becomes 1, B becomes 2, and Z becomes 26. This tool encodes text into numbers and decodes numbers back into letters, entirely in your browser. It is a favourite in kids' puzzle books and became widely known through the animated series Gravity Falls, which hid A1Z26 messages in its credits.
To encode, every letter is mapped to its 1-based position and the numbers within each word are joined by a separator you choose (a hyphen by default), while spaces between words are preserved. To decode, the tool splits each group of digits on the separator, converts each number 1–26 back to a letter, and rebuilds the words. Numbers outside the 1–26 range are flagged as invalid so you always get a clean result rather than a garbled one.
You can pick a hyphen, comma, dot, or space as the separator, and switch to 0-based indexing (A=0 … Z=25) for variants that count from zero. Non-letter characters are skipped when encoding. As a quick example, HELLO encodes to 8-5-12-12-15, and the classic Gravity Falls sign-off decodes straight back to plain letters.