ROT13 Converter

Apply ROT13 letter substitution cipher to text with support for ROT5 (digits) and ROT47 (ASCII) variants.

Tested tool guide Tested browser tools Checked August 16, 2026

What ROT13 Converter does, with a checked example

ROT13 is a substitution cipher that shifts every letter 13 places through the alphabet, wrapping from Z back to A. The tool also offers ROT5, which does the same half-turn for digits 0-9, and ROT47, which shifts the 94 printable ASCII characters instead. The surprise for most users is that the shift is exactly half the character set, so applying the tool twice restores the original text: the same button encodes and decodes. The other surprise is that ROT47 is not ROT13 plus ROT5 - it turns letters into punctuation, not into the ROT13 result. And none of the three is encryption; a fixed-shift cipher is trivially breakable.

Worked example

A concrete input and expected output from the current implementation.

Input

Hello, World!

Expected output

Uryyb, Jbeyq!

Each letter moves 13 places forward through the alphabet, wrapping past Z: H becomes U, e becomes r, and so on, while the comma, space, and exclamation mark pass through unchanged and case is preserved. Shift 13 places again and Uryyb, Jbeyq! becomes Hello, World! again, because ROT13 is its own inverse.

How the result is produced

The half-turn alphabet

The alphabet splits into two halves of 13: A-M and N-Z. Each letter maps to its counterpart 13 places on, so A becomes N and N becomes A, and likewise B/O, C/P, on through M/Z. Because 13 is exactly half of 26, the operation is its own inverse - ROT13 applied twice returns the original text - so one button serves both directions. Case is preserved; digits, punctuation, and spaces pass through.

ROT5 and ROT47

ROT5 applies the same half-turn to digits: 0 swaps with 5, 1 with 6, up to 4 with 9, while letters pass through. ROT47 instead shifts the 94 printable ASCII characters, from ! to ~, by 47 places, so spaces, punctuation, and letters all move; since 47 is half of 94 it is self-inverse too. ROT47 of a letter is not its ROT13 image: A becomes p, not N.

Good uses

Hiding a spoiler, puzzle answer, or plot twist in a forum post, chat message, or code comment so it is unreadable at a glance, while anyone who wants to see it can decode it with a single paste.
Recovering plaintext from ROT13 or ROT47 text encountered in old Usenet archives, alternate reality games, puzzle hunts, or deliberately scrambled sample data - pasting it back in decodes it, because the transform is symmetric.
Obfuscating a short plain-ASCII string such as a config value or test fixture with ROT47, which garbles letters, digits, and punctuation alike so it no longer reads as meaningful text in a log, diff, or screenshot.

Limits and checks

ROT13, ROT5, and ROT47 provide zero security. They are fixed-shift ciphers that anyone who recognizes the scheme can decode by hand; never use them for passwords, tokens, or anything that genuinely needs protection.
The variants are separate modes, not a stack. ROT13 leaves digits alone, ROT5 leaves letters alone, and ROT47's letter output differs from ROT13's. Text encoded with one variant, decoded with another, comes out as nonsense.
Each mode touches only its own range: ROT13 leaves digits, punctuation, and non-ASCII text as-is, and ROT47 leaves non-printable characters such as tabs and line breaks alone. A result that is only partly readable usually means the source mixed modes or contains out-of-range characters.

Common questions

Why does running the same tool twice give me back my original text?

Each shift is exactly half of the characters it covers: 13 of 26 letters, 5 of 10 digits, 47 of 94 printable ASCII. Shifting by half the ring twice returns every character to its starting position, so encoding and decoding are the same operation. That is by design - it is why a single button serves both directions.

Can I use this to keep something private?

No. These are classic rot ciphers with a single fixed shift, understood for centuries, and anyone who knows the scheme can decode the text by hand. Use them for casual obfuscation - spoilers, puzzles, or hiding an answer from an accidental glance. For real protection use a proper encryption tool. Everything here runs in your browser, so nothing you paste is transmitted anywhere, but the transform itself carries no secrecy.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.