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🔐 Cipher Decoder
Professional online cryptography service. Learn, encode and decode texts online using historical and modern cryptographic methods.
Supported ciphers and codes
The application supports the most popular classical ciphers and encoding systems used for centuries
Caesar Cipher
A classical substitution cipher where each letter is shifted by a fixed number of positions in the alphabet. Used by Julius Caesar to encrypt military communications.
Example: A → D (shift by 3)
ROT13
Special case of Caesar cipher with a shift of 13 positions. Popular in internet communities for hiding spoilers and jokes.
Example: HELLO → URYYB
Atbash Cipher
Ancient monoalphabetic cipher where the first letter of the alphabet is replaced with the last, the second with the second-to-last, etc. Biblical origin.
Example: A → Z, B → Y, C → X
Morse Code
System for encoding letters, numbers and punctuation marks using sequences of dots and dashes. Used in telegraphy and radio communication.
Example: SOS → ... --- ...
Polybius Square
Ancient substitution cipher using a 5×5 grid where each letter is represented by a pair of digits corresponding to its position in the square. Invented by Greek historiographer Polybius.
Example: HELLO → 23 15 31 31 34
Fractional Cipher
Cipher where the alphabet is divided into groups, and each letter is replaced with a fraction. The denominator is the group number, the numerator is the position in the group. Example: for 4-letter groups ABCD=1, EFGH=2, G → 3/2 (3rd position in 2nd group).
Example: GAFA → 3/2 1/1 2/2 1/1 (groups: ABCD=1, EFGH=2...)
And more in the cipher decoder...
View all ciphers✨ Why Choose Our Tools?
Professional cryptographic tools with advanced features and modern interface
Lightning Fast
All operations are performed locally in your browser for maximum speed and security.
100% Secure
Your data never leaves your device. No server processing, complete privacy guaranteed.
Works Offline
PWA technology allows you to use the tools even without internet connection.
Educational
Learn cryptography through practice with detailed explanations and examples.
🛠️ Available Tools
Comprehensive set of cryptographic and steganographic tools
Classical Ciphers
- 🏛️ Caesar Cipher - shift-based substitution
- 🔄 ROT13 - simple letter replacement
- 🔀 Atbash - alphabet reversal cipher
- 📡 Morse Code - dots and dashes
- 🔢 Polybius Square - coordinate encoding
- 🧮 Fractional Cipher - mathematical approach
Steganography
Hide secret messages within innocent-looking text. Advanced techniques for covert communication that appear as normal content to casual observers.
- 📝 Text-based hiding methods
- 🔤 Invisible character encoding
- 📖 Content-preserving techniques
📚 Learn Cryptography
Dive into the fascinating world of secret codes and hidden messages. From ancient ciphers to modern encryption, discover the art and science of cryptography.