ROT13 ("rotate by 13") shifts every letter in the text 13 positions forward in the alphabet. A becomes N, B becomes O, and so on. Because there are 26 letters, applying the same shift twice returns the original text.

Is ROT13 the same for encoding and decoding?

Yes. ROT13 is self-inverse — applying it once encodes the text, applying it a second time decodes it back. This tool works for both directions.

Does ROT13 affect numbers or punctuation?

No. Only the 26 letters of the Latin alphabet (A–Z, a–z) are affected. Digits, spaces, and all other characters pass through unchanged.

How do you solve a ROT13 cipher?

Shift every letter back 13 positions, which is the same as shifting forward 13 because the alphabet has 26 letters. Paste the text above and the answer appears instantly — no manual counting needed.

Is ROT13 a secure cipher?

No. ROT13 provides no cryptographic security and is trivially reversible. It is used solely to obscure text from casual glancing — for example, hiding spoilers — not to protect sensitive information.

Is my text sent to a server?

No. All processing happens entirely in your browser using JavaScript. Nothing you type is transmitted anywhere.

ROT13 Decoder

Paste ROT13-encoded text and instantly decode it — or encode plain text — since ROT13 is its own inverse.

Input

Only A–Z letters are shifted; digits and punctuation pass through unchanged.

Decoded Output

Summary

ROT13 is a simple letter-substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. Because the alphabet has 26 letters, applying ROT13 twice returns the original text, making encoding and decoding identical operations. This tool converts any input instantly in your browser with no data sent to any server.

How it works

Paste or type your ROT13-encoded text into the input box.
The decoded output appears instantly below as you type.
Letters A–Z and a–z are shifted by 13; all other characters (numbers, punctuation, spaces) are left unchanged.
Click "Copy Output" to copy the decoded text to your clipboard.
Use "Swap" to move the output back to the input for a second pass.
Click "Clear" to reset both fields.

Use cases

Decode spoilers posted in ROT13 on forums and social media.
Reveal puzzle answers hidden with ROT13 encoding.
Quickly encode text you want to obscure from casual readers.
Verify ROT13 output when building or testing encoding scripts.
Decode newsgroup or mailing-list messages that use ROT13 for off-topic content.
Teach students about basic substitution ciphers and their limitations.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu

ROT13 Decoder

Use the ROT13 Decoder

Summary

How it works

Use cases

Frequently Asked Questions