ROT13 Encoder & Decoder
Encode and decode ROT13 — the Caesar cipher with a fixed shift of 13 that is its own inverse, popular for hiding spoilers and puzzle answers.
What is ROT13?
ROT13 ("rotate by 13") replaces each letter with the one 13 places further along the alphabet. Since the alphabet has 26 letters, applying ROT13 a second time brings the text back to normal, so a single operation both encodes and decodes.
How to use it
- Type or paste your text.
- The rotated text appears instantly.
- Tap Copy to save it.
What ROT13 is used for
ROT13 is a long-standing internet convention for hiding text in plain sight — spoilers, puzzle answers, and joke punchlines. It offers no real security; it simply makes text unreadable at a glance until the reader chooses to rotate it back.
How it works
Only the 26 letters are rotated; digits, spaces, and punctuation are left alone and letter case is preserved. A becomes N, B becomes O, and so on, with the second half of the alphabet wrapping back to the first.
More codes and ciphers
Explore the rest of the family: the Caesar Cipher, Atbash, Vigenère, and A1Z26. For other encodings, try the Morse Code Translator and the Binary Translator.
Free and private
This ROT13 tool runs entirely in your browser — free, with no sign-up, and nothing you type is uploaded or stored.
Frequently asked questions
- What is ROT13?
- ROT13 replaces each letter with the one 13 places after it in the alphabet. Since the alphabet has 26 letters, applying ROT13 twice returns the original text, so the same operation both encodes and decodes.
- What is ROT13 used for?
- It is commonly used online to hide spoilers, puzzle answers, and punchlines in plain sight — readers apply ROT13 to reveal the hidden text when they choose.
- Does ROT13 affect numbers?
- No. Standard ROT13 only rotates the 26 letters; digits, spaces, and punctuation are left unchanged, and case is preserved.
- Is it free and private?
- Yes — everything runs in your browser with no sign-up, and nothing is uploaded.
More free tools
- Morse Code TranslatorTranslate text to Morse code and decode it back, hear it as adjustable-speed sound with a visual flasher, and read the full Morse alphabet, number, and punctuation chart.
- Roman Numeral ConverterConvert numbers to Roman numerals and back, turn any date into Roman numerals for tattoos, and read the full chart from 1 to 1000.
- Binary TranslatorTranslate text to binary code and back, convert between decimal and binary numbers, and read the full binary alphabet chart.
- NATO Phonetic AlphabetSpell any word or name in the NATO phonetic alphabet (Alpha, Bravo, Charlie…), hear it read aloud, and browse the full chart with pronunciations, numbers, and the police alphabet.
- Braille TranslatorTranslate English text to Grade 1 Braille and Braille back to text, and read the full Braille alphabet and number chart.
- Hex to TextConvert hexadecimal to readable text and text to hex instantly, both directions, with a full hex ASCII reference chart. Private and works offline.