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ToolWrenApply the classic ROT13 cipher, which rotates each letter 13 places through the alphabet. Because 13 is half of 26, the same operation both encodes and decodes.
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ROT13 is a free, private online tool that lets you apply the ROT13 letter-rotation cipher online. It runs entirely in your browser, so nothing you enter is uploaded to a server.
Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.
ROT13 ("rotate by 13") is a simple substitution cipher that shifts every letter 13 positions: A↔N, B↔O, and so on. Non-letters are left unchanged. It's a special case of the Caesar cipher.
Applying ROT13 twice returns the original text, because shifting by 13 and then 13 more equals a full 26-letter rotation. So one button both encrypts and decrypts.
ROT13 hides spoilers, puzzle answers and punchlines from casual view. It provides no real security and should never be used to protect sensitive data.
ROT13 ('rotate by 13') is a special case of the Caesar cipher that shifts every letter 13 places through the alphabet - A becomes N, B becomes O, and so on. It is the best-known simple letter cipher on the internet, used not for security but for lightly hiding text that should not be read accidentally.
The alphabet has 26 letters, and 13 is exactly half of that. So shifting by 13 twice brings you back to where you started: ROT13 applied to ROT13 returns the original text. This means one operation both encodes and decodes - there is no separate decrypt step, which is part of its charm and simplicity.
ROT13 is a convention for obscuring text, not securing it. Online forums and newsgroups have long used it to hide spoilers, puzzle answers, punchlines and offensive jokes, so readers must make a deliberate choice to reveal them. It provides no protection whatsoever - decoding is trivial - but that is exactly the point: it is a politeness tool, not a security one.
ROT13 only affects letters. A variant called ROT5 rotates digits, and ROT47 rotates a wider range of ASCII characters including symbols. ROT13 is also a Caesar cipher with shift 13, so the Caesar tool here can reproduce it (and any other shift). Non-letters always pass through unchanged.
Type or paste text and the ROT13 result appears instantly; the same action reverses it. Use it to hide or reveal spoilers and puzzle answers, or as a simple cryptography teaching example. Everything runs in your browser.