About this tool
The Vigenère cipher shifts each letter by the corresponding keyword letter, preserving case and leaving non-letters untouched. Everything runs locally in your browser.
Frequently asked questions
What happens to spaces and punctuation?
Non-letter characters pass through unchanged, and the keyword does not advance on them, so only letters are enciphered.
Is the keyword case-sensitive?
No. The keyword is treated case-insensitively, while the case of each message letter is preserved in the output.