About the Palindrome Checker
A palindrome reads the same forward and backward, like "racecar", "level" or the number 12321. Type or paste a word, a number or a whole sentence and the Palindrome Checker tells you at once whether it is one.
Sentence palindromes only work when you ignore spaces, punctuation and capital letters, so the checker does that by default. "A man, a plan, a canal: Panama" is checked as "amanaplanacanalpanama" and passes. It also ignores accents, which matters for palindromes in French, Spanish and other languages.
Next to the verdict you see the text exactly as it was checked, the same text reversed, and the longest palindrome hidden inside it. You can also check a whole list, one line at a time. Everything runs in your browser.
How to use it
- Type or paste your textEnter a word, a number, a date or a sentence. You can also click one of the examples below the box.
- Read the resultThe result box says "Yes, it is a palindrome" or "No, it is not a palindrome" and updates as you type.
- Compare both directionsChecked as shows the text after spaces, punctuation, capitals and accents are removed. Reversed shows the same text backward, so you can see where they differ.
- Look for hidden palindromesLongest palindrome inside shows the longest stretch that reads the same both ways, even when the whole text does not.
- Check a listTurn on "Check each line on its own" to test many words at once. A table shows Yes or No for every line.
Key features
Sentence palindromes
Spaces and punctuation are ignored by default, so phrases like "Was it a rat I saw?" are recognized.
Case and accents ignored
"Racecar" passes, and accented letters count as their plain form, so "Ésope reste ici et se repose" works.
Numbers and dates
Check numbers like 12321 or dates like 02/02/2020, which reads 02022020 without the slashes.
Longest palindrome inside
Finds the longest palindromic part of any text, such as "kayak" in a longer sentence.
Line by line
Check a whole word list at once and see how many lines are palindromes.
Every option can be turned off
Switch off ignoring case, punctuation or accents for a strict, character-by-character check.
Examples
Classic palindromes
| You type | Result |
|---|---|
| racecar | Yes, 7 characters checked |
| Never odd or even | Yes, 14 characters checked |
| Was it a rat I saw? | Yes, 13 characters checked |
| Mr. Owl ate my metal worm | Yes, 19 characters checked |
| A man, a plan, a canal: Panama | Yes, 21 characters checked |
| Hello world | No, reversed it reads dlrowolleh |
The character count only includes letters and digits, because spaces and punctuation are ignored.
Palindrome dates
Dates become palindromes when their digits read the same both ways. 02/02/2020 is checked as 02022020, and 12/02/2021 as 12022021. Both pass. Note that it depends on the date format: written month first, 12/02/2021 is December 2, 2021.
What the options change
| Option turned off | Input | Result |
|---|---|---|
| Ignore case | Racecar | No, because R and r now differ |
| Ignore spaces and punctuation | Never odd or even | No, reversed it is "neve ro ddo reven" |
| Ignore accents | Ésope reste ici et se repose | No, because é and e now differ |
Finding a palindrome inside a sentence
Type My favorite word is kayak, really. The sentence is not a palindrome, but Longest palindrome inside shows kayak. For "Hello world" it finds owo, across the space between the two words.
Checking a list
With "Check each line on its own" turned on, this list gives 3 of 4 lines are palindromes:
racecar
hello
Step on no pets
levelTips
- If a sentence fails by one letter, compare Checked as with Reversed from both ends. The first letter that differs shows where the sentence breaks the pattern.
- Writing your own palindrome? Start in the middle with a short palindrome like "kayak" or "noon" and add matching letters on both sides.
- Use the line mode to filter a word list: paste hundreds of words, one per line, and read the Yes rows from the table.
- Turn off all three options when you need an exact check, for example for a code, an ID or a test case in a programming exercise.
- Looking for palindrome dates? Remember that the same date can pass in one format and fail in another, such as month first or day first.
Common mistakes and limits
- Forgetting that every letter counts"Step on no pets" is a palindrome; "Step on no pet" is not. Dropping a single letter breaks the mirror.
- Expecting words to be reversed, not lettersA palindrome reverses letter by letter. "You can cage a swallow, can't you, but you can't swallow a cage, can you?" reads the same word by word, but the checker says No, because its letters do not.
- Leaving the strict options on by mistakeWith Ignore case or Ignore spaces and punctuation off, almost no sentence passes. Turn them back on for normal sentence palindromes.
- Searching very long text for hidden palindromesLongest palindrome inside only runs on texts up to 400 characters after cleaning. Longer text is still checked as a whole.
- Expecting line mode to ignore the longest searchIn line mode, Longest palindrome inside still looks at all lines joined together, so its result can span two lines.