Caesar Cipher (ROT13)
Last updated: June 1, 2026Encode and decode shifted text.
Caesar Cipher (ROT13) is a free online tool to encode and decode shifted text. It runs entirely in your browser, so your files never leave your device — nothing is uploaded. There's no sign-up, no watermark, and it works on any modern browser on desktop or mobile.
How to use Caesar Cipher (ROT13)
The Caesar Cipher tool encodes and decodes text by shifting each letter a fixed amount, including the classic ROT13. Numbers, spaces and punctuation are left unchanged. Free, instant and runs in your browser.
- 1Choose Encode or Decode and set the shift.
- 2Enter your text (or tap ROT13).
- 3Copy the result.
Any shift + ROT13
Use any shift 0–25, or one-tap the classic ROT13.
Both directions
Encode a message or decode one you received.
Free & private
Runs on your device with no sign-up.
Caesar Cipher (ROT13) — frequently asked questions
What is a Caesar cipher?
A simple substitution cipher that shifts every letter by a fixed number of places in the alphabet. A shift of 13 is ROT13.
How do I decode a Caesar cipher?
Switch to Decode and enter the same shift used to encode it — the tool reverses the shift.
Is it free?
Yes, completely free.
Share this tool
Send it to someone who needs it or save the link for later.
More text tools
View allBionic Reading Converter
Bold word-starts to read faster.
Word Counter
Count words, characters and reading time.
Case Converter
UPPERCASE, lowercase, Title Case and more.
Lorem Ipsum Generator
Generate placeholder text fast.
JSON Formatter
Format, validate and minify JSON.
Online Notepad
A clean notepad that auto-saves.