All tools · 🔤 Encode / Decode
🔁 ROT13 / Caesar Cipher
ROT13 is a classic substitution cipher that shifts each letter by 13 positions — encoding and decoding are the same operation. This tool also lets you set any shift 0-25 (Caesar cipher). Useful for puzzles, CTFs, and spoiler protection.
Examples
Hello, World!Uryyb, Jbeyq!attack at dawndwwdfn dw gdzqGur cnffjbeq vf gehfgThe password is trustFrequently asked questions
Is ROT13 secure?
No — it is trivially reversible. Used historically for jokes and spoiler protection on Usenet, never for real security.
Why does ROT13 decode itself?
Because the alphabet has 26 letters and 13 is half. Apply the shift twice and you are back where you started.
What about non-letters?
Numbers, punctuation, and spaces pass through unchanged. Case is preserved.
About this tool
ROT13 / Caesar Cipher runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.
Related tools
- 🔢 Hex ↔ ASCII / Text — Convert text to hexadecimal byte sequence and back. UTF-8 aware.
- 🔤 Base64 Encoder / Decoder — Encode text to Base64 or decode a Base64 string back to UTF-8 text.
- 🔐 Hash Generator — Generate MD5, SHA-1, SHA-256, SHA-384, SHA-512 hashes from text input.
Why this tool
vs typical free web-tool sites
| 1vw | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for premium features) |
| Ads inside the tool | No | Yes (banner + video) |
| Data sent to server | No (browser-only) | Yes (inputs analyzed for ads) |
| Total tools | 96 | Often <20 or scattered across sites |
| Bookmarkable URL per tool | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Open source | Yes | No |