Palindrome Checker

How to use the palindrome checker

1. Type or paste a word or a sentence in the input box. The answer appears as you type; you can also click Check.
2. Choose what to ignore: Ignore case, Ignore accents (é = e) and Ignore spaces and punctuation are ticked by default, which is how palindromic sentences are usually judged.
3. Read the verdict. If the text is not a palindrome, the tool names the first pair of characters that don’t match and gives their positions.
4. To test a whole list of words at once, tick Check each line separately: each line gets its own result in a table, with a count of the palindromes found.

Reading the mirror view

The Mirror view shows your text with the pairs that are compared. The first compared character is paired with the last, the second with the second-to-last, and so on toward the middle. Pairs that match are shown in green, pairs that differ in red, and the center character of an odd-length palindrome is outlined. Characters that the options ignore, such as spaces and commas, are faded.

Below, the Compared: line shows exactly what the tool compared after applying your options, and Reversed: shows the same sequence backwards. A text is a palindrome when these two lines are identical. For “A man, a plan, a canal: Panama!”, both read amanaplanacanalpanama.

The longest palindrome inside

Even when a text isn’t a palindrome, it often contains one. The tool finds the Longest palindrome inside your text with Manacher’s algorithm, which checks every possible center in a single pass, so it stays instant on long texts. The palindrome is underlined in the mirror view and shown in the original spelling: in “Hello, Laval!”, it finds Laval. Its length counts only the compared characters.

Accents, emoji and other tricky characters

The tool works on user-perceived characters (grapheme clusters), not on raw code units. An accented letter typed as one character or as a letter plus a combining accent counts as the same single character, and an emoji with a skin tone or a flag stays one unit instead of being split in half. This matters when you turn off Ignore spaces and punctuation: then emoji, symbols and spaces take part in the comparison as whole characters.

With Ignore accents (é = e), “Ésope reste ici et se repose” is a palindrome, as French tradition expects. Turn the option off to require exact accents. Ligatures such as œ are kept as they are, so they only match another œ.

Famous palindromes to try

• Words: kayak, level, racecar, radar, rotor, noon
• “Was it a car or a cat I saw?”
• “Never odd or even.”
• “Madam, in Eden, I’m Adam.”
• French: “Ésope reste ici et se repose”, “Engage le jeu que je le gagne”.