Palindrome checker
Paste a word, a sentence or a whole paragraph. The tool tells you if it reads the same forwards and backwards and shows the longest palindromic part it contains. It works with any alphabet and with emoji.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Type or paste your text. The answer appears under the result box.
- Turn the three options on or off to decide what is ignored.
- The box shows the longest palindromic part. For a true palindrome, it is the whole text from its first to its last compared character.
How it works
The tool splits the text into visible characters, drops the ones the options skip, and compares the first with the last, the second with the second to last and so on. To find the longest palindromic part, it grows a palindrome outwards from every possible centre and keeps the longest.
Worked example
“A man, a plan, a canal: Panama” with the default options becomes “amanaplanacanalpanama”, which reads the same both ways. In “racecar level” the longest palindromic part is “racecar” with 7 characters, ahead of “level” with 5. With Ignore case off, “Abba” is not a palindrome because A and a differ; its longest part is “bb”.
Tips
Texts longer than 10,000 characters are not checked. A single character or a single letter always counts as a palindrome of length one, so the longest part is never empty when the text has something to compare.
Frequently asked questions
What is a palindrome?
A palindrome reads the same forwards and backwards, like "level" or "madam". Whole phrases count too when you ignore spaces and punctuation, for example "Was it a car or a cat I saw?".
What exactly do the three options skip?
Ignore case treats A and a as the same letter. Ignore spaces skips spaces, tabs and line breaks. Ignore punctuation skips marks such as commas, colons, quotes and hyphens. Symbols and emoji are always compared.
How does it handle emoji and accents?
The text is compared in visible characters, so an emoji with a skin tone or a flag counts as one character. A letter with an accent is different from the plain letter, so é and e do not match.
What is the longest palindromic substring?
It is the longest unbroken part of your text that is itself a palindrome. In "babad" it is "bab". If several parts are equally long, the first one is shown. Skipped characters inside the part are shown as they were typed.