Character Frequency Counter — Character frequency analysis counts how often each character appears in a piece of text. It is the first step in classical cryptanalysis (substitution ciphers leave statistical fingerprints), a quick way to detect what language a text is in, and a useful sanity check when generating sample or test data.
Counting happens entirely in your browser.
Was Character Frequency Counter useful?
Character Frequency Counterとは？
Character frequency analysis counts how often each character appears in a piece of text. It is the first step in classical cryptanalysis (substitution ciphers leave statistical fingerprints), a quick way to detect what language a text is in, and a useful sanity check when generating sample or test data.
Paste any text and get a ranked list of every character with its count, sorted from most to least frequent. Toggle case sensitivity and whitespace handling to fine-tune the result.
使い方
-
Paste text
Any length — works for sentences, paragraphs, or large corpora.
-
Pick options
Toggle case sensitivity and whether to include whitespace.
-
Read the ranked list
The most frequent character is at the top.
使用例
English text
In English, "e" is by far the most common letter.
結果： e 12, t 9, a 8, o 7, i 6, n 6, s 6, h 5, r 5, …
Cryptanalysis hint
A frequency table for ciphertext can crack simple substitution ciphers.
結果： Most-frequent character matches a likely plaintext "e"
よくある質問
関連ツール
Last reviewed: 2026-09-25