Caesar Cipher
Encode or decode text with a classic Caesar shift cipher, including the famous ROT13 preset, computed live in your browser.
Encoded Output
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Frequently Asked Questions
Is my data sent to a server when using the Caesar Cipher tool?
No. The Caesar Cipher tool is a fully client-side utility. All data processing, calculations, and conversions are handled locally in your browser. No input text, payloads, or keys are uploaded to any external server.
What is ROT13?
ROT13 is just a Caesar cipher with a fixed shift of 13. Since the alphabet has 26 letters, shifting by 13 twice returns you to the original text — it's self-inverse, so the same operation both encodes and decodes.
Is the Caesar Cipher secure for protecting sensitive data?
No. The Caesar cipher is a classical, historical cipher meant for obfuscation and puzzles, not real security — it only has 25 possible shifts and can be brute-forced instantly. For real confidentiality, use a modern authenticated cipher like the site's AES-based Encrypt/Decrypt tool instead.
What happens to numbers, spaces, and punctuation?
Only letters (A-Z, a-z) are shifted. Numbers, spaces, and punctuation pass through completely unchanged, and letter case is preserved.
Does the Caesar Cipher tool store history or cache my inputs?
No. The application runs entirely in browser memory. Once you refresh the tab, navigate away, or close the window, all inputted details, logs, and outputs are completely cleared.
Is the Caesar Cipher tool compatible with mobile devices?
Yes. The interface is optimized to be fully responsive. You can perform calculations, conversions, and formats on all modern mobile, tablet, and desktop web browsers.
Does the Caesar Cipher tool work offline?
Yes. Once loaded, all code and assets required to run the Caesar Cipher tool reside in your browser cache, enabling offline use without an active network connection.