Category: Developer tools
Caesar Cipher Converter
Encode and decode text with an adjustable-shift Caesar cipher
Encode or decode text with a Caesar cipher using any shift from 1 to 25. Each letter moves forward or backward through the alphabet by the chosen amount while numbers, spaces and punctuation stay unchanged. Runs entirely in your browser.
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Everything on this page is processed in your browser. Nothing is uploaded.
What this tool does
The Caesar cipher is one of the oldest known ciphers: every letter in the message is replaced by the letter a fixed number of positions further along the alphabet, wrapping from Z back to A. ROT13 is simply a Caesar cipher with the shift fixed at 13; this tool lets you pick any shift from 1 to 25 and choose whether to encode (shift forward) or decode (shift backward) with it. Case is preserved and non-letter characters pass through untouched, so punctuation and spacing stay readable.
How to use it
- Choose Encode to shift text forward or Decode to shift it back.
- Set the shift amount (1–25) and type or paste your text.
- Copy the result with the copy button.
Privacy
This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.
Frequently asked questions
- How is this different from ROT13?
- ROT13 is a Caesar cipher with the shift permanently set to 13. This tool lets you use any shift from 1 to 25, including 13.
- What happens to numbers and punctuation?
- Only letters A–Z and a–z are shifted; digits, spaces and punctuation are left exactly as typed.
- Is my text uploaded anywhere?
- No. The shift is computed locally in your browser and nothing is sent to a server.