Send Secret Messages

Encode personal messages, notes, and private communications with a simple substitution cipher.

No cal iniciar sessió

Shifts each letter by 13. Self-inverse — applying it twice returns the original.

Input

Output

Gur dhvpx oebja sbk whzcf bire gur ynml qbt.

Messages tips

🕵️

For passing notes or sharing a message only certain people can read, agree on a shift or Vigenère keyword in advance.

💡

Vigenère with a long keyword is significantly harder to crack than Caesar. Use a 8–12 character keyword for practical obscurity.

📱

Send the encoded text via any messaging platform. Only people who know the cipher type and key can decode it without computational help.

⚠️

These classical ciphers are not cryptographically secure for sensitive data. For real privacy, use end-to-end encrypted messaging apps.

Introdueix

Enter your data into the tool above. Everything stays local to your browser.

Processa

The tool processes your data instantly in your browser using JavaScript. No server, no waiting.

Descarrega

Get your result instantly. Nothing is stored after you leave the page — complete privacy.

✓Completament gratuït — sense costos ocults, mai

✓No cal compte, correu electrònic ni inici de sessió

✓Els fitxers no surten mai del teu dispositiu

✓Sense cap límit de mida de fitxer

✓Sense marques d'aigua en cap sortida

Encode and Decode ROT13

Use ROT13 to obscure text — the go-to cipher for s

Create Caesar Cipher Puzzles

Encode hidden messages in Caesar cipher for scaven

Learn Classical Cryptography

Explore Caesar, Atbash, and Vigenère ciphers to un

Apply the Atbash Cipher

Reverse the alphabet with Atbash: A becomes Z, B b