About ROT13
A simple caesar substitution cipher which rotates alphabet characters by the specified amount (default 13).
Input: binary bytes. Output: binary bytes.
Format reference: ROT13 background and specification
Example
Use “Try example” to load this public sample and its settings, then run it.
Input
Hello, world!
Result
Uryyb, jbeyq!
Parameters
| Parameter | Default value | Input and choices |
|---|---|---|
| Rotate lower case chars | true | On or off |
| Rotate upper case chars | true | On or off |
| Rotate numbers | false | On or off |
| Amount | 13 | Number |
Before interpreting the result
Use the exact key encoding, mode, padding and IV expected by the source system. Historical ciphers are useful for learning and analysis. Encoding alone provides no confidentiality.
How to use this page
- Paste your input or open a local file.
- Adjust tool options if needed, then choose Run tool.
- Copy the result or download the original output bytes.
Inputs and results are not added to the public catalogue or saved in the URL. Processing happens in your browser; HTTP Request and DNS over HTTPS send the requests you explicitly run. Files up to 128 MiB can be opened; decompression and image tools may have smaller processing limits. Large results have a shortened preview. Text and HTML downloads use UTF-8; binary downloads preserve output bytes. Pasted text follows browser newline handling; open a file when exact input bytes matter.