How to Encrypt Text with Caesar, ROT13 and Vigenère

To encrypt text with a classic cipher, open the ByteTools Text Cipher, choose Caesar, ROT13 or Vigenère, set a shift or keyword if needed, toggle Encrypt, and type your message — the transformed text appears instantly, ready to copy. Decoding is the same flow with the toggle flipped to Decrypt. Everything runs in your browser, so no message ever leaves your device.

This guide walks through each cipher step by step and shows exactly what to enter so you can encode and decode with confidence.

The three ciphers at a glance

Step-by-step: encrypting a message

1. Pick your cipher. Choose Caesar, ROT13 or Vigenère depending on how much control you want over the transformation.
2. Set the parameter. For Caesar, enter a shift such as 3. For Vigenère, type a keyword like LEMON. ROT13 needs no input at all.
3. Toggle to Encrypt. Make sure the direction switch is set to encode rather than decode.
4. Type your message. Enter the plaintext and watch the ciphertext update. Letters shift while spaces, digits and punctuation pass through untouched, and case is preserved.
5. Copy the result. One click sends the ciphertext to your clipboard, ready to paste into a note, chat or puzzle.

Worked example

With Caesar and a shift of 3, Attack at Dawn becomes Dwwdfn dw Gdzq — notice the capital letters stay capital and the space is preserved. Apply ROT13 to Hello and you get Uryyb; run ROT13 again and it returns to Hello, which is why it is perfect for hiding spoilers.

Decrypting a message

Decoding mirrors encoding. Select the same cipher, enter the same shift or keyword the sender used, flip the toggle to Decrypt, and paste the ciphertext. For Caesar you must know the shift; for Vigenère you need the exact keyword; for ROT13 you simply re-apply it. Without the right parameter the output stays scrambled, which is the whole point.

Why it runs in your browser

All encoding and decoding happen locally in JavaScript. Nothing is uploaded, logged or stored, so your messages remain entirely on your device — and the tool keeps working offline as a PWA once loaded. That said, these are historical ciphers built for puzzles, learning and light-hearted secret notes, not for protecting passwords or sensitive data. Treat them as educational fun, never as real security.

Try the Text Cipher — free and 100% in your browser.

FAQ

Which shift should I use for a Caesar cipher?

Any number from 1 to 25 works. A shift of 3 is the classic historical choice, while 13 turns Caesar into ROT13. Larger shifts are no harder to break but keep the ciphertext looking different from common examples.

What makes a good Vigenère keyword?

A longer keyword with varied letters produces a more thoroughly mixed ciphertext than a short one. Just remember the recipient needs the exact same keyword, spelled identically, to decode the message.

Do I lose my punctuation and capital letters?

No. Only letters are shifted; spaces, numbers and punctuation are left exactly as they are, and upper and lower case are preserved, so the ciphertext keeps the shape of the original.

Can I decode a message someone else encrypted?

Yes, as long as you know which cipher and which shift or keyword they used. Select the matching settings, switch to Decrypt, and paste their ciphertext to recover the plaintext.

Related free tools

• Text to Binary Converter — encode messages as ones and zeros.
• Morse Code Translator — turn text into dots and dashes.
• NATO Phonetic Alphabet Converter — spell messages aloud clearly.
• Reverse Text — flip text for another layer of playful obfuscation.

Built by ByteVancer

ByteTools is a free product of ByteVancer, a software and web development studio building web apps, SaaS, and custom software. When a project needs real, modern cryptography and secure engineering rather than classroom ciphers, explore what ByteVancer can build for your team.