Vigenère Cipher — Polyalphabetic Cipher Online
Encode and decode text with the classic Vigenère cipher using a custom keyword key.
Keyword (letters only)
Plaintext
Ciphertext
- The Vigenère cipher shifts each letter by the corresponding letter in the repeating keyword
- Non-alphabetic characters (spaces, digits, punctuation) are preserved unchanged
- Case is preserved — uppercase input stays uppercase, lowercase stays lowercase
Frequently Asked Questions about Vigenère Cipher
- Is Vigenère Cipher completely free to use?
- Yes, Vigenère Cipher is 100% free with no sign-up, no watermarks, and no usage limits.
- Is my data private?
- Vigenère Cipher runs entirely in your browser — no data is ever sent to our servers. Your content stays on your device.
- Does it work offline?
- Once the page has loaded, Vigenère Cipher works fully offline in your browser — no internet connection is required.
- Is the encoding/decoding fully reversible?
- Yes, all encoding operations are fully reversible. Use the same tool or a corresponding decoder to reverse the operation.
- Does Vigenère Cipher work on mobile and tablet?
- Yes, Vigenère Cipher is fully responsive and works in all modern browsers on desktop, tablet, and mobile.
This tool runs entirely in your browser. No data is ever sent to our servers.