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Vigenere Cipher

Encrypt and decrypt text with a keyword using the Vigenere cipher.

Your text and keyword

Non-letter characters are kept in place and do not advance the key.

How to use the Vigenere Cipher

  1. Type or paste the text you want to transform.
  2. Enter a keyword made of letters.
  3. Click Encrypt or Decrypt, then copy the result.

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Frequently Asked Questions

Common questions about the free online vigenere cipher.

It is a polyalphabetic substitution cipher that shifts each letter by a different amount taken from a repeating keyword.
Use the same keyword and the Decrypt button, which shifts letters backwards instead of forwards.
Yes. Because the shift changes with every letter it resists simple frequency analysis far better than a Caesar cipher, though it is still not secure.
Only letters are used as the key; digits, spaces and symbols are stripped out automatically.
They are copied unchanged and do not consume a letter from the keyword.
It was famously broken using the Kasiski examination and frequency analysis once the key length is known.
Yes. The tool is fully responsive and works in any modern browser on desktop, tablet and phone.
Yes, it is completely free with no account required.

Last updated: October 10, 2026