ROT13 Encoder and Decoder
Rotate every letter by 13 to lightly obscure text. Applying ROT13 a second time gives you the original back, so one box does both jobs.
One operation that undoes itself
ROT13 is a Caesar cipher with a shift of exactly 13. Because the alphabet has 26 letters, rotating forward by 13 and then doing it again rotates a full 26 and lands you back where you started, so the same button both scrambles and unscrambles. It is the classic way to hide a spoiler or a punchline in plain sight without really encrypting anything. Only A to Z and a to z move; digits, spaces, and symbols pass through untouched, and it all runs right here in your browser.
When you want it hidden for real
ROT13 is reversible by anyone, so treat it as a toy, not a lock. When you need text that only you can read, Relic keeps an end-to-end encrypted memory of everything you copy, searchable across all your devices and kept for as long as you like. The toy is free, and the genuinely private memory is the upgrade.
Frequently asked questions
What is ROT13 and how do I use it?
ROT13 rotates every letter 13 places through the alphabet, so A becomes N and N becomes A. Paste your text and the result appears instantly. Because 13 is exactly half of 26, applying ROT13 again undoes it, so this single box both scrambles and unscrambles.
Why does the same button encode and decode?
ROT13 is a Caesar cipher with a fixed shift of 13. Rotating forward by 13 twice moves a full 26 letters, which lands you back on the original character, so encoding and decoding are the exact same operation. There is even a button to send the result back into the input if you want to run it again.
What happens to numbers, spaces, and punctuation?
Only the letters A to Z and a to z are rotated. Digits, spaces, symbols, and any non-letter characters pass through completely unchanged, and letter case is preserved, so an uppercase letter stays uppercase.
Is ROT13 secure?
No, and it is not meant to be. ROT13 is a toy that anyone can reverse in seconds with no key, so treat it as a way to hide a spoiler or a punchline in plain sight, never as protection. For an adjustable shift see the caesar-cipher tool, and for text that only you can read use encrypt-text.
Does my text leave the page?
No. The rotation runs entirely in your browser with no network calls, so whatever you paste stays on your device.