Palindrome Checker — Words, Phrases & Numbers, Instant

Check whether a word, phrase, sentence or number is a palindrome. By the usual convention, spaces, punctuation and capitals are ignored — so "A man, a plan, a canal: Panama" passes — and you can switch to the strict letter-for-letter rule. When something is not a palindrome, the mismatched characters are highlighted so you can see how close it came.

Paste a longer passage and the tool also finds the longest palindrome inside it and lists every palindromic word.

How to use Palindrome Checker

Type or paste anything: a word, a sentence, a number, a date.
Read the verdict and the two lines beneath it — the text as compared, and its reverse — with any differences marked.
Untick the options for the strict check where "Level" (capital L) and "level" are different, or spaces count.
Try the samples for the classics, or paste a paragraph to hunt for palindromes inside it.

What counts as a palindrome

A palindrome reads the same forwards and backwards. For single words that is unambiguous: level, racecar, rotator, deified. For phrases the accepted rule — the one used in puzzles, competitions and every famous example — ignores spaces, punctuation and letter case, comparing only letters and digits. Under that rule "Was it a car or a cat I saw?" qualifies; under the strict rule almost no sentence does, which is why the strict rule is the option and not the default.

Famous ones

A man, a plan, a canal: Panama — the best known, coined in 1948 for the canal's builder.
Madam, I'm Adam — the oldest joke in the genre.
Never odd or even · Do geese see God? · Mr. Owl ate my metal worm
Sator Arepo tenet opera rotas — a Latin word square from Pompeii that is a palindrome in every direction.
Numbers: 12321, 1001, and dates like 02/02/2020 (the first fully symmetric date in 909 years).

Accents, emoji and other alphabets

Comparison is by Unicode character, so é is one character and equals only é, not e; Greek, Cyrillic and Arabic palindromes work as well as English ones; an emoji is one character. If you want accents ignored, strip them first with the case converter's plain-text options.

The longest palindrome inside a text

Every string contains palindromes — single letters trivially, and doubled letters like ee. The tool reports the longest run of three or more characters, which is a small puzzle in itself: try a paragraph of ordinary prose and see what turns up. Programmers will recognise this as the classic "longest palindromic substring" interview question; the method here expands outward from every centre, which is fast enough to run on every keystroke.

For anagrams and other rearrangements, see the anagram solver; to reverse text outright, the word scrambler has a reverse mode.

Frequently asked questions

Do spaces and punctuation count?

By default, no — the standard convention compares only letters and digits, ignoring case, so "Madam, I'm Adam" is a palindrome. Untick the options for the strict character-by-character check.

Is a single letter or an empty string a palindrome?

A single character is, trivially — it reads the same both ways. An empty input has nothing to compare, so the tool shows no verdict rather than a meaningless "yes".

Does it work with numbers and dates?

Yes. 12321 and 1001 are palindromic numbers; dates like 02/02/2020 or 12/02/2021 pass once the slashes are ignored. Numbers are compared as digit characters, not values, so 0110 counts.

What is the longest palindrome word in English?

Commonly cited: tattarrattat (12 letters, coined by James Joyce), detartrated (11), and in everyday use rotavator and redivider (9). The longest single word most people know is racecar or deified.

Why does the highlight show mismatches in pairs?

A palindrome check compares the first character with the last, the second with the second-last, and so on. Each mismatch is one pair, so both members are marked — showing you exactly which positions break the symmetry.