Character Frequency Analyzer
Analyze individual character frequencies and percentage breakdown in text.
Character & Word Frequency Analyzer
About Character Frequency Analyzer
The Text Character & Letter Frequency Distribution Analyzer counts letter occurrences (A–Z), digits, punctuation, and whitespace, calculating relative percentages ($f/N \times 100$), Shannon Entropy, Morse code weights, and comparative cryptanalysis vs standard English frequency (ETAOIN SHRDLU).
How to Use Character Frequency Analyzer
Step 1
Paste your text or upload a document into the analyzer.
Step 2
Toggle case sensitivity and ignore whitespace options as needed.
Step 3
Inspect the letter frequency bar chart and Shannon entropy score.
Step 4
Click "Export CSV" or copy top frequency statistics.
Practical Use Cases for Character Frequency Analyzer
Classical Cryptanalysis & Substitution Cipher Breaking
Analyze letter frequency distributions to crack Caesar ciphers, Monoalphabetic substitution ciphers, and Vigenère ciphers.
Information Entropy & Compression Auditing
Calculate Shannon entropy to measure text randomness, information density, and theoretical compression limits.
Input & Output Examples
Analyzing Character Frequency of Sample Text
Text: "The quick brown fox jumps over the lazy dog"
Top Letters: O (9.1%), E (7.0%), T (7.0%), H (4.5%), U (4.5%) | Shannon Entropy: 4.28 bits/char | Total Chars: 43
Key Features & Performance
- ✓Counts frequency of all characters: Letters (Case-sensitive / Insensitive), Digits, Whitespace, and Symbols.
- ✓Compares text letter distribution against Standard English Frequency (ETAOIN SHRDLU).
- ✓Calculates Shannon Information Entropy ($H = -\\sum p_i \\log_2 p_i$) and Index of Coincidence ($IC$).
- ✓Sortable frequency table and interactive bar chart distribution.
- ✓100% Client-Side memory execution.
- ✓1-Click Export CSV frequency report.
Key Terminology & Definitions
ETAOIN SHRDLU
The approximate order of frequency of the twelve most commonly used letters in the English language.
Shannon Information Entropy
A measure of the average uncertainty or information content per character in a text message, measured in bits.