Free Palindrome Checker Online

The Palindrome Checker is a free online tool that determines whether a word, phrase, or sentence reads the same forwards and backwards.

Yes, it is completely free with no registration required. All checking happens client-side in your browser.

Yes, the Palindrome Checker can ignore spaces, punctuation, and capitalization when determining if text is a palindrome.

Absolutely. The Palindrome Checker processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the Palindrome Checker is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the Palindrome Checker in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Yes, the Palindrome Checker handles text of any length with fast, real-time processing. Since everything runs in your browser, performance depends on your device but works well for most use cases.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The Palindrome Checker works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

That phrase is a palindrome because of how you decide which characters "count." If you read it literally, the spaces, commas, colon, and capital letters do not line up when reversed, so it fails an exact match. But if you strip everything except letters and digits and lowercase them, you get "amanaplanacanalpanama," which reads identically forwards and backwards. This is why the tool defaults to Alphanumeric Only mode, ignoring case, spaces, and punctuation. You can also pick Exact Match, Case Insensitive, Ignore Spaces, or Ignore Punctuation to see how each rule changes the verdict. Switching modes re-evaluates instantly, so you can watch a phrase flip between "Palindrome" and "Not a Palindrome" depending on what you choose to ignore. Paste the phrase above and toggle the modes to see it for yourself.

A number is a palindrome when its digits read the same in both directions, such as 121, 1331, or 12321. You check it the same way you would a word: reverse the sequence of digits and compare it to the original. The Numbers tab does this automatically, but it also goes a step further by testing the binary representation of the value, not just its decimal form. When a number reads the same in both decimal and binary, it is flagged as a "Double Palindrome." That is rarer than it sounds, since most palindromic decimals are not palindromic in base two. Palindromic primes, which are both prime and palindromic, include 2, 3, 5, 7, 11, 101, 131, 151, 181, and 191. Enter a whole number in the Numbers tab to check both bases at once.

A near-palindrome is text that almost reads the same backwards but has a few characters out of place. Instead of just rejecting it, the checker measures how far off it is: it counts how many characters would need to change for the string to mirror perfectly, then shows a similarity percentage. So "abcba" scores 100 percent, while a string needing two edits scores lower and tells you exactly two characters are wrong. When your text is not a palindrome, the tool also highlights the longest palindromic substring hidden inside it, the longest mirror-symmetric run of characters within your input. This turns a flat "no" into useful, measurable feedback, which is handy when you are tweaking a phrase or debugging palindrome logic. Type any non-palindrome above to see the change count, similarity score, and longest substring.

Most palindromes are letter-level: the individual characters read the same backwards, like "racecar" or "level." A word-level palindrome works on whole words instead of letters, so the sequence of words is symmetric even though the letters are not. A sentence like "You can cage a swallow can't you, but you can't swallow a cage can you" reads the same by its order of words, not its letters. The checker runs both tests, reporting whether your text is a palindrome by characters and, separately, whether its words form a palindrome in sequence. It also lists any individual palindromic words it finds inside a longer passage. This distinction matters in puzzles and creative writing, where word palindromes are a separate craft from letter ones. Paste a sentence above and the tool will check it both ways at once.

There is no single official answer, but a few famous contenders show up repeatedly. "Tattarrattat," coined by James Joyce in Ulysses to imitate a knock on a door, is twelve letters long and often cited as the longest palindrome to appear in a major literary work. "Detartrated" is another long real-ish chemistry term sometimes mentioned. Among sentence palindromes, classics like "Never odd or even," "Was it a car or a cat I saw," and the canal-Panama line are the most quoted. Long single-word palindromes are rare because every added letter must mirror one on the other side, which quickly becomes impossible in natural spelling. The tool's Fun Facts tab collects these famous examples, and you can click any of them to load it straight into the checker. Try pasting "tattarrattat" above to confirm it for yourself.