ROT13 / ROT47 Encoder & Decoder
Rotate letters, digits or all printable ASCII — the same step encodes and decodes.
Rotate text
Rotates the letters A–Z by 13 places (A ↔ N). Digits, spaces and punctuation stay as they are.
Type in either box: the other one updates as you type.
Character table: what each rotation swaps
ROT13 swaps these pairs both ways; every other character stays as it is.
- A swaps with N
- B swaps with O
- C swaps with P
- D swaps with Q
- E swaps with R
- F swaps with S
- G swaps with T
- H swaps with U
- I swaps with V
- J swaps with W
- K swaps with X
- L swaps with Y
- M swaps with Z
- a swaps with n
- b swaps with o
- c swaps with p
- d swaps with q
- e swaps with r
- f swaps with s
- g swaps with t
- h swaps with u
- i swaps with v
- j swaps with w
- k swaps with x
- l swaps with y
- m swaps with z
ROT5 swaps these pairs both ways; every other character stays as it is.
- 0 swaps with 5
- 1 swaps with 6
- 2 swaps with 7
- 3 swaps with 8
- 4 swaps with 9
ROT18 swaps these pairs both ways; every other character stays as it is.
- A swaps with N
- B swaps with O
- C swaps with P
- D swaps with Q
- E swaps with R
- F swaps with S
- G swaps with T
- H swaps with U
- I swaps with V
- J swaps with W
- K swaps with X
- L swaps with Y
- M swaps with Z
- a swaps with n
- b swaps with o
- c swaps with p
- d swaps with q
- e swaps with r
- f swaps with s
- g swaps with t
- h swaps with u
- i swaps with v
- j swaps with w
- k swaps with x
- l swaps with y
- m swaps with z
- 0 swaps with 5
- 1 swaps with 6
- 2 swaps with 7
- 3 swaps with 8
- 4 swaps with 9
ROT47 swaps these pairs both ways; every other character stays as it is.
- ! swaps with P
- " swaps with Q
- # swaps with R
- $ swaps with S
- % swaps with T
- & swaps with U
- ' swaps with V
- ( swaps with W
- ) swaps with X
- * swaps with Y
- + swaps with Z
- , swaps with [
- - swaps with \
- . swaps with ]
- / swaps with ^
- 0 swaps with _
- 1 swaps with `
- 2 swaps with a
- 3 swaps with b
- 4 swaps with c
- 5 swaps with d
- 6 swaps with e
- 7 swaps with f
- 8 swaps with g
- 9 swaps with h
- : swaps with i
- ; swaps with j
- < swaps with k
- = swaps with l
- > swaps with m
- ? swaps with n
- @ swaps with o
- A swaps with p
- B swaps with q
- C swaps with r
- D swaps with s
- E swaps with t
- F swaps with u
- G swaps with v
- H swaps with w
- I swaps with x
- J swaps with y
- K swaps with z
- L swaps with {
- M swaps with |
- N swaps with }
- O swaps with ~
About the ROT13 / ROT47 Encoder & Decoder
ROT13 replaces every letter with the one 13 places further along the alphabet, so A becomes N and N becomes A. The alphabet has 26 letters, so doing it twice brings you back where you started: the same step both encodes and decodes. Since the early days of Usenet people have used it to hide spoilers, punchlines and puzzle answers from an accidental glance — not from anyone who wants to read them.
This page rotates text as you type, in both directions: type in either box and the other one updates. Besides ROT13 it offers ROT5 (the digits 0–9 by 5), ROT18 (ROT13 and ROT5 together) and ROT47, which rotates all 94 printable ASCII characters from ! to ~, so numbers and punctuation are scrambled too. Everything runs in your browser.
How to use it
- Choose the rotation: ROT13 for letters, ROT5 for digits, ROT18 for both, or ROT47 for letters, digits and symbols.
- Type or paste text into either box. The other box shows the rotated text straight away.
- To decode, paste the encoded text into the same box: each rotation is its own inverse, so there is no separate decode step. If the other box reads like English, the page says so.
- Copy the result or download it as a .txt file. Swap moves the two texts between the boxes.
Examples
Why did the chicken cross the road?
Jul qvq gur puvpxra pebff gur ebnq?
Capitals stay capitals; spaces and punctuation are untouched.
The Quick Brown Fox Jumps Over The Lazy Dog.
%96 "F:4< qC@H? u@I yF>AD ~G6C %96 {2KJ s@8]Letters, digits and symbols all change; only the spaces show where the words were.
Room 42 at 9:30
Ebbz 97 ng 4:85
Letters move 13 places and digits 5 places, so 4 becomes 9 and 0 becomes 5.
Common uses
- Hiding spoilers, quiz answers or punchlines in forum posts, chats and emails, so readers only see them if they choose to.
- Solving or setting puzzles, geocaching clues and escape-room riddles that use ROT13 or ROT47.
- Reading text that a program or a CTF challenge stored in ROT13 or ROT47.
- Teaching how substitution ciphers work before moving on to the Caesar cipher and real encryption.
How each rotation works
- ROT13: A–Z and a–z, shifted by 13 of 26 places. A↔N, B↔O … M↔Z.
- ROT5: 0–9, shifted by 5 of 10. 0↔5, 1↔6 … 4↔9.
- ROT18: ROT13 and ROT5 at the same time (13 + 5 = 18), also called ROT13.5.
- ROT47: the ASCII characters with codes 33 (
!) to 126 (~), 94 in all, shifted by 47: a character with code c becomes 33 + ((c − 33 + 47) mod 94).!becomesPand~becomesO.
Each shift is exactly half of its alphabet, which is why applying it twice returns the original. Open Character table under the tool to see every pair.
ROT13 is not encryption
There is no key: anyone who knows (or guesses) that ROT13 was used can undo it instantly, and frequency analysis breaks it even without that knowledge. Use it to hide text from a casual glance only — never for passwords, personal data or anything secret. ROT13 is a Caesar cipher with a shift of 13; the Caesar Cipher tool handles every other shift and can find an unknown one for you.
Limitations
- Only ASCII characters are rotated. Accented letters (é, ñ), other alphabets, ₹ and emoji pass through unchanged, so a mostly non-English text stays readable.
- ROT47 leaves spaces (and line breaks) where they are, so word lengths remain visible.
- The “reads like English” hint uses English letter frequencies and needs at least 20 letters; it says nothing for other languages or short texts.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
How do I decode ROT13?
Paste the ROT13 text into either box: the other box shows the decoded text. Decoding is the same operation as encoding, because shifting by 13 twice is a full turn of the 26-letter alphabet.
Is ROT13 secure?
No. It has no key and is reversed in a moment by anyone, so it only hides text from people who are not trying to read it. For anything private use real encryption with a strong key.
What is the difference between ROT13 and ROT47?
ROT13 changes only the 26 letters, so numbers and punctuation stay readable. ROT47 rotates all 94 printable ASCII characters from ! to ~, so digits and symbols are scrambled too, and the result looks much less like words.
Why does the same button encode and decode?
ROT13 shifts by 13 and the alphabet has 26 letters; ROT5 shifts 10 digits by 5; ROT47 shifts 94 characters by 47. Each shift is half a full turn, so doing it twice returns every character to where it started.
Is ROT13 the same as a Caesar cipher?
Yes — a Caesar cipher with a shift of 13. Other shifts are not their own inverse, so they need separate encode and decode steps; the Caesar Cipher tool does both and can crack an unknown shift.
Does it keep capital letters and line breaks?
Yes. Capital letters stay capitals, and line breaks, spaces and any characters a rotation does not cover are copied exactly.