Caesar Cipher & ROT13

Text Tools

Encode and decode text with a letter shift

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Shift (1–25, use 13 for ROT13)
Full guide, 3 min readCaesar cipher: why only 25 keys means anyone can crack itRead the story behind this tool →
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History

All history →

Caesar Cipher & ROT13 — at a glance

Encrypt or decrypt text with the classic Caesar cipher by shifting letters by any number.

Your input
ABC (shift 3)
Run
Result
DEF

How to use it — step by step

A message in English letters.

1

Paste your input

Paste or type your content into the big input box. Try a sample if you want to see it work.

2

Choose options

Pick the mode and options that fit what you need.

3

Run cipher

Press the button. The result is created instantly on your device.

4

Copy the result

Check the output and press Copy to use it anywhere.

Pro tips

Small things that make the result better.

✦Decode with the same shift number you used to encode.
✦ROT13 is its own reverse — encode twice and you get the original.
✦Only A–Z letters change; numbers and symbols stay.

Quick facts

Freeno signup, no limit
Instantresult in a moment
Privatenothing is uploaded
Any devicephone, tablet or PC

Frequently Asked Questions

Is the Caesar cipher secure?+

No. It only has 25 possible keys and is easy to crack. Use it for fun and learning, never for real secrets.

Is my data safe?+

Yes. Everything runs inside your own browser. Your text, files and images are never uploaded to any server.

Is this tool really free?+

Yes — completely free, no signup, no watermark and no usage limit.

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