Is it safe to use the ROT13 / Caesar online?

Yes — and ours is safer than most. Many free online tools quietly upload your files to their servers to do the work. We don't. Everything happens inside your browser on your own device, so your files never reach the internet. There's no upload step, no server copy, and no way for us (or anyone else) to see what you're working on.

Are my files uploaded to a server?

No. There's no server-side processing here. The whole tool is a tiny app that runs in your browser — we don't even have a server that could receive your files. You can confirm this by opening your browser's network tab while you use the tool: nothing leaves your device.

Do I need to sign up or pay?

No. There's no account, no email collection, no credit card. The tool is free to use as much as you want, on as many files as you want. We're supported by a few unobtrusive ads on the page — not by your data.

Not at all. ROT13 is a toy cipher, used today only for hiding spoilers. For real encryption use AES Encrypt.

Why does ROT13 work both ways?

Because the alphabet has 26 letters and 13+13=26, applying ROT13 twice returns the original.

ROT13 & Caesar Cipher

Classic letter-shift ciphers. ROT13 is its own inverse — encoding and decoding are the same. Other Caesar shifts let you specify a shift from 1 to 25, or brute-force show all rotations to spot the readable one.

Features

ROT13 (default) and arbitrary Caesar shifts
Preserves case and non-alphabetic characters
Brute-force mode lists all 25 possible shifts
Live conversion as you type

How to rot13 & caesar cipher

Paste text — Type or paste any text.
Pick shift — 13 for ROT13. Any 1-25 for general Caesar.
Read output — Or use Brute force to see all 25 shifts at once.

Frequently asked questions

Is it safe to use the ROT13 / Caesar online?: Yes — and ours is safer than most. Many free online tools quietly upload your files to their servers to do the work. We don't. Everything happens inside your browser on your own device, so your files never reach the internet. There's no upload step, no server copy, and no way for us (or anyone else) to see what you're working on.
Are my files uploaded to a server?: No. There's no server-side processing here. The whole tool is a tiny app that runs in your browser — we don't even have a server that could receive your files. You can confirm this by opening your browser's network tab while you use the tool: nothing leaves your device.
Do I need to sign up or pay?: No. There's no account, no email collection, no credit card. The tool is free to use as much as you want, on as many files as you want. We're supported by a few unobtrusive ads on the page — not by your data.
Is ROT13 secure?: Not at all. ROT13 is a toy cipher, used today only for hiding spoilers. For real encryption use AES Encrypt.
Why does ROT13 work both ways?: Because the alphabet has 26 letters and 13+13=26, applying ROT13 twice returns the original.