ROT13 & Caesar
Rotate A–Z by a fixed number. ROT13 uses shift 13 and applying it twice restores the original.
0 characters
Encoded result
Classical ciphers can be reversed without a secret or broken through frequency analysis. Base64, binary, and hexadecimal only change representation. Never use them to protect passwords, private messages, tokens, or confidential files.
Choose the right transformation
Ciphers change letters; encodings change representation
ROT13, Caesar, Atbash, and Vigenère operate mainly on Latin letters. Base64, binary, and hex operate on UTF-8 bytes and therefore preserve emoji and multilingual Unicode text.
- Select a methodChoose a classical cipher or byte encoding.
- ConfigureSet direction, shift, keyword, casing, or byte separator.
- TransformValidate, copy, reverse, reuse, or download.
Transformation reference
Atbash
Maps A to Z, B to Y, and so on. Encoding and decoding are the same operation.
Vigenère
Uses repeating keyword shifts. Historically important, but not secure against modern analysis.
Base64, binary & hex
Represent UTF-8 bytes for transport, inspection, and interoperability—not secrecy.
Frequently asked questions
Why did older Base64 tools fail on emoji?
Browser btoa() accepts byte-like characters, not arbitrary Unicode. This tool explicitly encodes UTF-8 bytes first.
How is binary decoded?
Binary groups are validated as exactly eight bits per UTF-8 byte, then decoded with a strict UTF-8 decoder.
Can negative Caesar shifts be used?
Yes. Shifts are normalized modulo 26, so negative and large-direction values behave consistently.