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ROT13 / Caesar Cipher error
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// about this tool

ROT13 / Caesar Cipher Online

Updated 2026-08-19

Encode and decode ROT13 and Caesar cipher text online for free. Type your text, pick a shift (13 for ROT13, or any value for a Caesar cipher), and SnapTools transforms it instantly in your browser. Nothing you enter is uploaded.

ROT13 is the classic "rotate by 13" cipher long used to hide spoilers and puzzle answers — apply it twice and you are back to the original. Set any other shift and you have a full Caesar cipher. Letters rotate while digits and punctuation stay put. It is perfect for puzzles and light obfuscation, but never for real security — these ciphers are trivial to break.

// how to use

  1. 1 Type or paste your text into the input panel on the left.
  2. 2 Choose the shift amount — 13 for classic ROT13, or any other value for a Caesar cipher.
  3. 3 Read the transformed text on the right, then copy or download it.

// examples

ROT13
Input
Hello
Output
Uryyb
ROT13 is its own inverse
Input
Uryyb
Output
Hello

// common uses

Hiding spoilers, answers, or punchlines in plain sight Solving or creating Caesar cipher puzzles Learning how substitution ciphers work Lightly obfuscating text that is not sensitive

// faq

Is my text uploaded to a server?
No. The cipher runs entirely in your browser, so your text never leaves your machine.
What is ROT13?
ROT13 shifts every letter 13 places through the alphabet. Because the alphabet has 26 letters, applying ROT13 twice returns the original text — encoding and decoding are the same operation.
How is a Caesar cipher different?
A Caesar cipher shifts letters by any chosen amount, not just 13. ROT13 is simply the Caesar cipher with a shift of 13. Set a different shift here to encode or decode any Caesar-shifted text.
Are numbers and symbols changed?
No. Only letters are rotated; digits, spaces, and punctuation pass through unchanged, and letter case is preserved.
Is this secure encryption?
No. ROT13 and Caesar ciphers are for obfuscation and puzzles, not security — they are trivial to reverse. Never use them to protect sensitive data.

// works with your data

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Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/rot13-caesar-cipher \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":"Hello"}'