// Security
ROT13 Encoder & Decoder online
Encode and decode text with ROT13, ROT5, and ROT47 substitution ciphers
by
CHUNKY
MUNSTER
MUNSTER
ROT13 Encoder & Decoder: scramble your text instantly with the classic 13-letter shift Caesar cipher tool. Designed for quick obfuscation on forums and in code, this utility provides a simple way to hide spoiler text or puzzle answers from casual view. Because the algorithm is symmetric, applying the rotation twice returns your original message, making it a fast and efficient Usenet cipher for developers and writers.
Our tool expands beyond basic letter rotation to include a ROT47 generator for printable ASCII characters and a ROT5 cipher for digits. This versatile substitution cipher online utility allows you to combine modes for a comprehensive "ROT18" effect, ensuring that your alphanumeric data is properly scrambled. By performing all processing locally in your browser, the software ensures that your sensitive notes never leave your machine, providing a secure environment for symmetric obfuscation without the need for complex cryptographic keys. Use it to streamline your text hiding tasks with technical precision and zero-latency performance.
No - it offers no real security. The original Usenet use case was hiding spoilers and punchlines, not protecting secrets. The cipher is symmetric and the key is published, so anyone can decode it instantly.
Both rotate by exactly half of the alphabet they cover (13 of 26 letters, 47 of 94 printable ASCII characters). Two rotations of half a cycle wrap all the way around, so encode and decode are the same operation.
ROT5 only touches digits 0–9 (5 ↔ 0, 6 ↔ 1, etc.) and leaves letters alone. Combine ROT13 + ROT5 ("ROT18") and you get a single pass that obfuscates both letters and digits.
It only operates on bytes 33–126 (printable ASCII). Anything outside that range - accented letters, emoji, CJK characters - passes through unchanged, so a paragraph of mixed scripts will be partially rotated.
Scramble your sensitive content today with this high-speed utility. Explore more Security tools at Chunky Munster and return to this ROT13 Encoder & Decoder for all your simple text obfuscation.