Send Secret Messages

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

Níl gá le logáil isteach

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.

Cuir isteach

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

Próiseas

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

Íosluchtaigh

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

✓Go hiomlán saor in aisce - gan aon chostais i bhfolach, riamh

✓Níl cuntas, ríomhphost ná logáil isteach ag teastáil

✓Ní fhágann comhaid do ghléas riamh

✓Níl aon teorainn le méid comhaid ar bith

✓Gan comhartha uisce ar aon aschur

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