ROT18 Encode & Decode
Combines ROT13 (letters) + ROT5 (digits) in one operation. This tool does both encode and decode on one page — just pick a mode, paste your text, and click. Everything runs on your device, nothing is sent to a server.
Everything runs in your browser. Your data is never sent to our servers.
Example
Example Input
Code42
Example Output
Pbqr97
How to Use
- 1Choose Encode or Decode mode at the top.
- 2Type or paste your text into the Input field.
- 3Click the button (or press Ctrl+Enter) to process. The result appears in the Output field.
- 4Click Copy to copy the result, or "Swap input/output" to quickly reverse the operation.
About ROT18
ROT18 is the combination of ROT13 and ROT5: letters are shifted 13 positions and digits 5 positions. It obscures text containing both letters and numbers.
How it works: apply ROT13 to letters and ROT5 to digits at the same time. Because both are symmetric, ROT18 is its own inverse — encode and decode are the same.
ROT18 is useful for hiding spoilers or answers that mix letters and numbers. Like other ROT variants, it is not secure encryption.
FAQ
Can this ROT18 tool both encode and decode?
Yes. This is a single page with a toggle — use Encode mode to transform text, and Decode mode to reverse it. No need for two separate pages.
Is my data sent to a server?
No. ROT18 is processed entirely in your browser. The text you enter never leaves your device.