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● Ciphers & Transforms

ROT13 Cipher Tool

ROT13 (Rotate by 13 places) is a specific case of the Caesar cipher which replaces a letter with the 13th letter after it in the Latin alphabet. Because the basic Latin alphabet has 26 letters, ROT13 is its own inverse; that is, to undo ROT13, the same algorithm is applied, so the same action can be used for encoding and decoding. It is a staple of early internet culture (Usenet) for hiding spoilers, punchlines, and offensive jokes from casual browsing.

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ROT13

A special case of Caesar cipher with a shift of 13

Properties:

  • Self-reversing
  • No key needed
  • Commonly used in online forums for spoilers
  • Example: "HELLO" → "URYYB" → "HELLO"

Cipher

0 characters

Output Text

0 characters
How this tool works Documentation & SEO

ROT13 (Rotate by 13 places) is a specific case of the Caesar cipher which replaces a letter with the 13th letter after it in the Latin alphabet. Because the basic Latin alphabet has 26 letters, ROT13 is its own inverse; that is, to undo ROT13, the same algorithm is applied, so the same action can be used for encoding and decoding. It is a staple of early internet culture (Usenet) for hiding spoilers, punchlines, and offensive jokes from casual browsing.

Obfuscate text instantly with ROT13. Perfect for hiding spoilers, punchlines, and puzzle solutions on forums. Simple, reversible text rotation.

Community managers hiding spoilers (movies/books) in forums
Geocachers encoding hints for cache locations
Developers needing a quick, reversible obfuscation method
Puzzle creators designing text-based riddles
Usenet archivists decoding historical posts
Key features
  • Symmetric algorithm (Apply once to encode, again to decode)
  • Standard 13-character rotation
  • Affects only A-Z and a-z characters
  • Leaves numbers and symbols untouched
  • Instant browser-based conversion
  • No key selection needed
Frequently Asked Questions FAQ
Why is ROT13 so popular despite being insecure?
Its popularity stems from convenience, not security. It provides a standard way to hide text (like a spoiler) that requires deliberate user action to reveal, without needing passwords or complex keys.
Does ROT13 affect numbers?
No, standard ROT13 only rotates the 26 letters of the alphabet. Numbers, punctuation, and whitespace remain exactly as they are. There are variants like ROT5 (for numbers) or ROT47 (for all ASCII), but this tool focuses on standard ROT13.
Can I use this for passwords?
Never. It offers zero security against anyone trying to read it. It is equivalent to writing a password backward or changing the font; it is merely obfuscation, not encryption.