How to Use the Cipher Frequency Analyzer
Enter ciphertext and this tool counts how many times each letter from A to Z appears, showing the frequency and share in a table. Since English letters aren't used equally often (E, T, and A are the most common), it uses that property to estimate the shift value of a Caesar cipher by running a chi-squared comparison against standard English letter frequencies for every possible shift from 0 to 25, then shows a decoded preview using the best match. It's useful for students studying cryptography, CTF competitors, or anyone curious about how classical ciphers work.
This tool is built specifically for Caesar ciphers and simple substitution ciphers that shift the alphabet — modern encryption methods like AES or RSA work on entirely different principles and cannot be decoded this way. Only English letters (A-Z) are counted; other alphabets, numbers, and symbols are excluded.
Frequently Asked Questions
It's built for frequency analysis of Caesar ciphers and simple substitution ciphers that shift the alphabet. It cannot decrypt modern encryption like AES or RSA.
It tests every shift from 0 to 25 and calculates a chi-squared statistic comparing the result to standard English letter frequencies, then picks the closest match.
Only English letters (A-Z) are counted. Characters from other alphabets, numbers, and symbols are excluded from the count.