Classical ciphers (ROT13, Caesar, Atbash, Vigenère), Morse code, the NATO phonetic alphabet and MIME email encodings. The ciphers here are educational — none of them is secure encryption. Everything runs locally in your browser.
Cipher and Communication Tools
- ROT13 Encoder and Decoder
Apply ROT13, ROT13.
- Caesar Cipher Encoder and Decoder
Shift letters by any amount from 1 to 25, or break an unknown Caesar cipher instantly by showing all 25 possible shifts at once.
- Atbash Cipher
Apply the Atbash substitution, which mirrors the alphabet so A becomes Z and B becomes Y.
- Vigenere Cipher Encoder and Decoder
Encrypt or decrypt with a repeating keyword, the classic polyalphabetic cipher.
- Morse Code Translator
Translate text to international Morse code and back, covering letters, digits and common punctuation, with configurable word separators.
- NATO Phonetic Alphabet Converter
Spell text out in the ICAO and NATO phonetic alphabet – Alfa, Bravo, Charlie – for reading codes aloud over phone or radio, and convert phonetic words back to text.
- Quoted-Printable Encoder
Encode text as quoted-printable (RFC 2045), the email transfer encoding that keeps mostly-ASCII text readable while escaping everything else.
- Quoted-Printable Decoder
Decode a quoted-printable email body back to readable text, resolving the escapes and removing soft line breaks.
- MIME Header Encoder and Decoder
Decode encoded words from email Subject and From headers, or build your own – the RFC 2047 mechanism that lets ASCII-only headers carry any language.
JWT and Token Tools
- JWT Decoder
Decode a JSON Web Token to inspect its header and payload, with registered claims explained and timestamps converted to dates.
- JWT Structure Validator
Check a JWT for structural problems – section count, Base64URL validity, JSON shape, the required alg field, claim types, expiry and the dangerous alg none case.
- JWT Encoder
Build and sign a demonstration JWT locally with HS256, HS384 or HS512.
