Isogram Checker
Check whether no letter repeats in text, case-insensitively, ignoring non-letter characters.
Description
Check whether an English text repeats any ASCII letter, ignoring case and non-letters.
An isogram contains no repeated letters. This checker follows the common English a-to-z puzzle convention and ignores spaces, punctuation, and digits.
When to use Isogram Checker
- Check a word-puzzle answer
- Test a phrase for repeated ASCII letters
- Compare isograms with pangrams
How the calculation works
Lowercased ASCII letters are inserted into a set. Encountering a letter already in the set returns false; every other character is skipped.
Interpreting the result
True means each ASCII letter appears at most once, not that all 26 letters appear. Non-ASCII letters are outside this definition.
Important limitations
- Accented and non-Latin letters are ignored.
- Language-specific case rules are not applied.