Stuck with a cipher or secret code? This free tool will help you identify the type of encryption, as well as give you guidance about solving it and any available cipher decoder. This tool uses AI/Machine Learning technology to recognize most common cipher types and codes.

This automatic cipher identifier uses Artificial Intelligence/Machine Learning to detect the type of encryption including Caesar Cipher, Vigenère Cipher (including the autokey variant), Beaufort Cipher (including the autokey variant), Playfair Cipher, Two-Square/Double Playfair Cipher, Columnar Transposition Cipher, Bifid Cipher, Four-Square Cipher, Atbash Cipher, and many more!

Read more about the ciphers and find links to cipher decoders below.

Caesar Cipher

The Caesar cipher, also known as a shift cipher is one of the oldest and most famous ciphers in history. While being deceptively simple, it has been used historically for important secrets and is still popular among puzzlers. In a Caesar cipher, each letter is shifted a fixed number of steps in the alphabet.

• Caesar Cipher Tool

Monoalphabetic Substitution Cipher

The monoalphabetic substitution cipher is one of the most popular ciphers among puzzle makers. Each letter is substituted by another letter in the alphabet. If it contains word boundaries (spaces and punctuation), it is called an Aristocrat. The more difficult variant, without word boundaries, is called a Patristocrat.

• Monoalphabetic Substitution Cipher Tool

Atbash Cipher

The Atbash Cipher is a really simple substitution cipher that is sometimes called mirror code. It is believed to be the first cipher ever used. To use Atbash, you simply reverse the alphabet, so A becomes Z, B becomes Y and so on.

• Atbash Cipher Tool

Vigenère Cipher

The Vigenère cipher was invented in the mid-16th century and has ever since been popular in the cryptography and code-breaking community. Despite being called the Vigenère cipher in honor of Blaise de Vigenère, it was actually developed by Giovan Battista Bellaso. The Vigenère cipher is an improvement of the Caesar cipher, by using a sequence of shifts instead of applying the same shift to every letter.

A variant of the Vigenère cipher, which uses numbers instead of letters to describe the sequence of shifts, is called a Gronsfeld cipher. Use the dedicated Gronsfeld cipher tool or its autosolver to decode it.

• Vigenère Cipher Tool
• Vigenère Cipher Autosolver

Vigenère Autokey Cipher

The Vigenère Autokey Cipher is a more secure variant of the ordinary Vigenère cipher. It encrypt the first letters in the same way as an ordinary Vigenère cipher, but after all letters in the key have been used it doesn’t repeat the sequence. Instead it begins using letters from the plaintext as key.

• Vigenère Autokey Cipher Tool
• Vigenère Autokey Cipher Autosolver

Beaufort Cipher

The Beaufort Cipher is named after Sir Francis Beaufort. It is similar to the Vigenère cipher, but uses a different "tabula recta". The plaintext letter is subtracted from the key letter instead of adding them. The Beaufort Cipher is reciprocal (the encryption and decryption algorithms are the same).

• Beaufort Cipher Tool
• Beaufort Cipher Autosolver

Beaufort Autokey Cipher

This cipher is similar to the Vigenère Autokey cipher, although it subtracts letters instead of adding them. The Beaufort Autokey Cipher is not reciprocal.

• Beaufort Autokey Cipher Tool
• Beaufort Autokey Cipher Autosolver

Playfair Cipher

The Playfair cipher was invented in 1854 by Charles Wheatstone, but named after lord Playfair who heavily promoted the use of the cipher. It is a polygraphic substitution cipher, which encrypts pair of letters instead of single letters.

• Playfair Cipher Tool

Columnar Transposition Cipher

In a columnar transposition cipher, the message is written in a grid of equal length rows, and then read out column by column. The columns are chosen in a scrambled order, decided by the encryption key.

• Columnar Transposition Cipher Tool

Railfence Cipher

The railfence cipher is a simple form of transposition cipher, where the text is written in a "zig-zag" pattern. It is then read out line by line from the top.

• Railfence Cipher Tool

Unknown Transposition Cipher

A lot of different transposition cipher variants exists, where the text is written in a particular pattern. Many can be solved manually by paper and pen. One of the more difficult variants is the double transposition cipher, which is equivalent to applying two columnar transposition ciphers.

• Double Transposition Cipher Tool

Bifid Cipher

The Bifid cipher was invented by the French amateur cryptographer Félix Delastelle around 1901, and is considered an important invention in cryptology. It uses a combination of a Polybius square and transposition of fractionated letters to encrypt messages.

• Bifid Cipher Tool

Two-Square Horizontal Cipher

The two-square cipher is also called "double Playfair". It is stronger than an ordinary Playfair cipher, but still easier to use than the four-square cipher. Depending on the orientation of the squares, horizontal or vertical, the cipher behaves slightly different.

• Two Square Cipher

Two-Square Vertical Cipher

The two-square cipher is also called "double Playfair". It is stronger than an ordinary Playfair cipher, but still easier to use than the four-square cipher. Depending on the orientation of the squares, horizontal or vertical, the cipher behaves slightly different.

• Two Square Cipher

Four-Square Cipher

The four-square-cipher was invented by the French amateur cryptographer Félix Delastelle. It is a digraph cipher, where each pair of letters in the ciphertext depends on a pair of letters in the plaintext. It uses four 5x5 squares to translate each digraph.

• Four Square Cipher Tool

Base64

Base64 is another favorite among puzzle makers. Basically it can be used to encode anything into printable ASCII-characters. Not seldom will the contents need further decoding.

Base64 is easy to recognize. It consists of letters (about 50% uppercase and 50% lowercase), as well as numbers, and often equal-characters (=) at the end.

• Base64 Decoder Tool

Morse Code

Morse Code is a highly reliable communications method, that can be transmitted in many ways, even during difficult and noisy environments. That makes it especially useful for puzzle games, where it is sometimes not fully obvious that a code is a Morse Code.

Morse Code can be recognized by the typical pattern: small groups of short and long signals. These signals could be actual tones, or other means such as lines, colors, letters or symbols.

• Morse Code Tool

Hexadecimal Codes

Hexadecimal Codes can represent ASCII, UTF-8, or more advanced encoding schemes. They can also represent the output of Hash functions or modern crypto algorithms like RSA, AES, etc.

Hexadecimal codes only use the digits 0-9 and letters A-F.

• Use the Binary Analysis Tool to find out more about your hexadecimal codes.

Binary Codes

Binary Codes can represent ASCII, UTF-8, or more advanced encoding schemes. They can also represent the output of Hash functions or modern crypto algorithms like RSA, AES, etc.

Binary codes only use the digits 0-1.

• Use the Binary Analysis Tool to find out more about your binary codes.

Octal Codes

Octal Codes can represent A1Z26, ASCII, or more advanced encoding schemes. They can also represent the output of Hash functions or modern crypto algorithms like RSA, AES, etc, even if they usually are presented in hexadecimal or binary format.

Octal codes only use the digits 0-7.

• The Octal number system

Decimal Codes

Decimal Codes can represent A1Z26, ASCII, or more advanced encoding schemes. They can also represent the output of Hash functions or modern crypto algorithms like RSA, AES, etc, even if they usually are presented in hexadecimal or binary format.

Decimal codes only use the digits 0-9.

• Use the A1Z26 Tool to convert A1Z26 codes.
• Use the Ascii Tool to convert Ascii codes.

ADFGX and ADFGVX Cipher

The ADFGVX cipher was used by the German Army during World War I. It was invented by Lieutenant Fritz Nebel and is a fractionating transposition cipher which combines a Polybius square with a columnar transposition. The name comes from the six possible letters used: A, D, F, G, V and X. It was an enhancement of the earlier ADFGX cipher.

• ADFGVX Tool
• ADFGX Tool

Plaintext

Secret messages can be hidden within plaintext, or something that looks like plaintext, using steganography techniques. Some of the most common steganigraphy techniques are the so called NULL cipher and the baconian cipher. Other possibilities are that the text is a riddle or using anagrams.

• Steganography
• NULL Cipher
• Baconian Cipher
• Anagram Solver

Other Ciphers

To find out more about your cipher, the following tools are recommended:

• Text Analysis Tool
• Frequency Analysis Tool

Unknown Format

• If your cipher consists of lines and dots, it could be a Pigpen Cipher.
• If your cipher has runes, you could translate them here.
• If your cipher has hardwritten symbols of men in various positions, it could be a dancing men cipher.
• If your cipher has combinations of colors, it could be a hexahue code.