Palindrome Checker
This is a palindrome
Under the rules selected. It reads the same in both directions.
- 21
- Characters compared
- No
- Word-level palindrome
The checker tests whether text reads the same in both directions, and shows you exactly what it compared. That matters more than the verdict: whether "A man, a plan, a canal: Panama" counts depends entirely on whether you ignore case, spaces and punctuation, and every checker makes that choice for you without saying so.
How it works
The text is normalised according to the four options, then compared with its own reverse. Both the forwards and backwards forms are displayed, so a surprising verdict can be traced to the normalisation rather than taken on trust.
- Ignore case is on by default. Without it, "Anna" fails because A and a are different characters.
- Ignore punctuation strips anything that is not a letter, digit or space. The colon in "canal: Panama" is why this one matters.
- Ignore spaces is what lets a phrase count at all; with it off, only single words and symmetrical phrases pass.
- Folding accents treats é as e, so "Ressasser" works in the same way its unaccented form does.
Reversal works on grapheme clusters rather than code units, so an accented letter written as a base plus a combining mark stays intact rather than having its accent relocated onto a neighbouring letter.
Two further properties are reported. A word-level palindrome reads the same word by word without being one letter by letter. "You can cage a swallow, can't you, but you can't swallow a cage, can you?" is the classic example. And when the text is not a palindrome, the longest palindromic run inside it is shown, found by expanding around every possible centre.
Examples
The canonical example
Text
A man, a plan, a canal: Panama
Result
Palindrome: compares "amanaplanacanalpanama"
Only with case, punctuation and spaces ignored. Turn off any one of the three and it fails, which is why the normalised form is shown.
A near miss
Text
Never odd or even!
Result
Palindrome: 15 characters compared
The exclamation mark is stripped along with the spaces. What remains, "neveroddoreven", is symmetrical.
Not a palindrome
Text
Almost a palindrome
Result
Not a palindrome: first mismatch at position 1
Comparing "almostapalindrome" with its reverse, the leading a does not match the trailing e, so it fails at the very first character. The longest palindromic run inside it is reported instead.
Frequently asked questions
Is "A man, a plan, a canal: Panama" really a palindrome?
Under the usual convention, yes, ignoring case, spaces and punctuation. Strictly character for character, no. There is no single correct answer, which is why the options are exposed and the compared text is shown rather than a bare verdict.
What is a word-level palindrome?
A phrase whose sequence of words reads the same in both directions, even though the letters do not. "You can cage a swallow, can't you, but you can't swallow a cage, can you?" is the classic example: the fifteen words reverse to the same order, while reading the letters backwards gives nonsense. It is reported separately because it is a genuinely different property.
Can a number be a palindrome?
Yes, and digits are treated exactly like letters. 12321 is a palindrome; 12345 is not. Dates are a common case. 02/02/2020 reads the same in both directions with the slashes ignored.
Why does folding accents change the answer?
Because é and e are different characters. With folding on, a word whose letters are symmetrical apart from an accent counts. With it off, the accent must appear symmetrically too. Which you want depends on whether you consider the accent part of the letter.
What is the longest palindrome inside my text?
The longest run of characters within the normalised text that is itself a palindrome, found by expanding around every possible centre. It is shown only when the whole text is not one, since otherwise the answer would just be the text again.
How is this different from the text reverser?
The reverser produces reversed text and mentions in passing when the result matches. This is built around the question: it exposes the normalisation rules, shows exactly what was compared, locates the first mismatch, and reports word-level and inner palindromes.