Decode a Vigenère cipher for a puzzle hunt

ARGs and geocache logs still love the classic cipher. Encrypt or decrypt with a keyword — learning-grade, not security.

Tools used in this guide

Vigenère cipher
Caesar cipher
Morse code converter

The job

A Vigenère message with a known key decodes mechanically: shift each letter back by the key letter's position, cycling the key. The tool does it for pasted text in both directions.

Key plus text

Choose decrypt, enter the keyword (letters only — LEMON), paste the ciphertext. Letters outside A–Z (digits, punctuation, spaces) pass through unchanged; case is preserved.

Worked check: LEMON + LXFOPV → ATTACK.
Encrypt direction re-hides plaintext with the same key — useful for building your own puzzle.

Not real security

Vigenère fell to frequency analysis in the 1800s. It's perfect for hunts, classrooms and escape rooms — never for protecting anything that actually matters. If you need real confidentiality, that isn't a cipher you paste in a browser.