Letter Frequency Analyzer
0 letters counted across 0 distinct letters.
No letters yet — type or paste some text above.
When to use this tool
Letter frequency analysis is the classic first step in breaking a substitution cipher. Paste the ciphertext from a Caesar, Atbash, affine, or keyword cipher and compare the distribution against English — E, T, A, O, I, N are the most common letters, so the tallest bars usually map to them. It is equally handy for puzzle and CTF challenges, language teaching, or just inspecting how lopsided a piece of text is.
Privacy and limitations
Everything runs locally in your browser; nothing is sent anywhere. This counts single letters A–Z only (case-insensitive) and ignores digits, punctuation, and spaces. It does not perform digram or trigram analysis, index of coincidence, or automatic cipher solving — it reports the raw distribution and leaves the cryptanalysis to you.