Palindrome Checker
Check if text is a palindrome and find the longest palindromic substring.
About Palindrome Checker
Instantly test whether any word, phrase, or sentence is a palindrome. Toggle options to ignore case, spaces, and punctuation — so classic examples like "A man, a plan, a canal: Panama" are correctly detected.
FAQ
- What is a palindrome?
- A palindrome is a word, phrase, or sequence that reads the same forwards and backwards — like "racecar" or "A man a plan a canal Panama".
- Why does "A man a plan a canal Panama" pass?
- With spaces and punctuation ignored, the normalized string amanaplanacanalpanama reads the same forwards and backwards.
- What is the longest palindromic substring?
- The longest contiguous sequence within the input text that is itself a palindrome.
ABOUT THIS TOOL
Type or paste any text to instantly check whether it reads the same forwards and backwards, and see the longest palindromic substring hiding inside it even if the whole phrase itself isn't a palindrome. The checker typically ignores spaces, punctuation, and letter case so that phrases like 'A man, a plan, a canal, Panama' are correctly recognized as palindromes rather than failing on formatting differences. It's a quick reference for word puzzle enthusiasts checking a clever phrase, students studying language and pattern structure, or anyone testing a string for a coding challenge involving palindrome detection. Because results update as you type, you can experiment with different phrases or word substitutions to see immediately whether they still qualify.
HOW TO USE
- Type or paste the text you want to check.
- Look at the result indicating whether it's a full palindrome.
- Check the longest palindromic substring shown below the result.
- Edit the text and watch the result update live.
- Try removing spaces or punctuation manually if you want to test strict character-by-character matching.
COMMON USE CASES
- Verifying a clever palindrome phrase you wrote for a puzzle or word game
- A student checking classic examples like 'racecar' or longer sentence-level palindromes for a linguistics assignment
- A programmer double-checking expected output while practicing a palindrome-detection coding exercise
- Someone testing whether a username, license plate idea, or short phrase happens to be a palindrome
- A puzzle designer searching for the longest palindromic substring within a longer piece of text for a hidden-word game
TIPS & COMMON MISTAKES
- Most palindrome checks ignore case and punctuation by default, so 'Racecar' and 'race car' may both register as palindromes even though they aren't identical strings
- Single characters and empty strings technically count as palindromes, which can be a surprising edge case if you're testing programmatically
- The longest palindromic substring doesn't have to be a real word, it's found purely by matching character patterns
- Numbers work the same way as letters here, '1221' is checked the same as any text-based palindrome
MORE QUESTIONS
- Does spacing or punctuation affect whether text counts as a palindrome?
- Typically no, the checker normalizes the text by stripping spaces, punctuation, and case differences first, which is why classic phrase palindromes like 'A man, a plan, a canal, Panama' pass even though the raw characters aren't a mirror image.
- What counts as the 'longest palindromic substring'?
- It's the longest continuous run of characters within your text that itself reads the same forwards and backwards, regardless of whether the full input is a palindrome.
- Can a single word be a palindrome even if the whole sentence isn't?
- Yes, a sentence can contain a palindromic word or substring in the middle while the sentence as a whole fails the check; that's exactly what the longest-substring result is designed to surface.
- Are palindrome checks case-sensitive?
- Generally no, because case sensitivity would make otherwise obvious palindromes fail on trivial capitalization differences, so most checkers normalize to lowercase before comparing.