The separator trap
A1Z26 looks trivial until someone writes 121. Is that 1-2-1 (aba), 12-1 (la) or 1-21 (au)? Without a separator the code is ambiguous and undecodable. That is the whole reason for the dash between numbers, and it is the commonest cause of an A1Z26 message that « does not work ».
This tool lets you pick the separator — dash, space, comma — and accepts any of them when reading.
Where you meet it
- Escape rooms and treasure hunts, as a first layer of encoding.
- Textbook puzzles, to introduce the idea of a cipher.
- Video games with hidden clues, often combined with a Caesar shift.
Like the Caesar cipher, A1Z26 offers no security whatsoever: it is a plain renaming of the letters, with no key.
Frequently asked questions
How do I handle two-digit numbers?
By always using a separator. 1-2 reads « ab » while 12 reads « l » — with no dash, nobody can tell.
Are accents supported?
Yes, they fold onto the base letter: é becomes 5 just like e. The A1Z26 alphabet has only 26 positions.
What happens to spaces?
They separate words in the output, which lets you recover the word boundaries when reading back.