ROT13 Encoder / Decoder
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What is ROT13?
ROT13 ("rotate by 13 places") is a simple letter substitution cipher that shifts each letter 13 positions in the alphabet. It's a special case of the Caesar cipher where encoding and decoding use the same transformation, since there are 26 letters in the alphabet. For example, 'A' becomes 'N', 'B' becomes 'O', and 'N' becomes 'A'. ROT13 is its own inverse, meaning applying it twice returns the original text.
How to Use ROT13 Encoder/Decoder
Simply enter your text in the input field, and the tool instantly applies ROT13 transformation. The same operation both encodes and decodes - there's no separate encode/decode mode needed. Letters are rotated while numbers, spaces, and punctuation remain unchanged. This makes ROT13 unique among ciphers: applying it twice returns your original message. Copy the result with one click.
Where ROT13 is Used
ROT13 is commonly used in online forums and newsgroups to hide spoilers, puzzle solutions, or potentially offensive content without truly encrypting it. It prevents accidental reading while remaining easily reversible. Many email clients and forum software have built-in ROT13 support. It's also used in geocaching for encoding hints, in programming for obfuscating simple strings, and as an educational example of substitution ciphers.
Understanding ROT13's Purpose
ROT13 provides no security and is not meant for encryption—it's trivially decoded by anyone who knows the algorithm. Instead, it serves as a "courtesy encoding" to prevent accidental exposure to spoilers or sensitive information. Think of it as a "click to reveal" mechanism in text form. Its beauty lies in its simplicity and self-inverse property, making it perfect for hiding content that users might want to decode easily themselves.